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feat(core): Add SpanBuffer implementation - #19204
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cc @isaacs tagged you for a review since you worked on the telemetry buffer and might see something I missed in this simplified implementation |
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Lms24 added a commit
that referenced
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Feb 13, 2026
This PR adds a simple span buffer implementation to be used for buffering streamed spans. Behaviour: - buckets incoming spans by `traceId`, as we must not mix up spans of different traces in one envelope - flushes the entire buffer every 5s by default - flushes the specific trace bucket if the max span limit (1000) is reached. Relay accepts at max. 1000 spans per envelope - computes the DSC when flushing the first span of a trace. This is the latest time we can do it as once we flushed we have to freeze the DSC for Dynamic Sampling consistency - debounces the flush interval whenever we flush - flushes the entire buffer if `Sentry.flush()` is called - shuts down the interval-based flushing when `Sentry.close()` is called - [implicit] Client report generation for dropped envelopes is handled in the transport Methods: - `add` accepts a new span to be enqueued into the buffer - `drain` flushes the entire buffer - `flush(traceId)` flushes a specific traceId bucket. This can be used by e.g. the browser span streaming implementation to flush out the trace of a segment span directly once it ends. Options: - `maxSpanLimit` - allows to configure a 0 < maxSpanLimit < 1000 custom span limit. Useful for testing but we could also expose this to users if we see a need - `flushInterval`- allows to configure a >0 flush interval Limitations/edge cases: - No maximum limit of concurrently buffered traces. I'd tend to accept this for now and see where this leads us in terms of memory pressure but at the end of the day, the interval based flushing, in combination with our promise buffer _should_ avoid an ever-growing map of trace buckets. Happy to change this if reviewers have strong opinions or I'm missing something important! - There's no priority based scheduling relative to other telemetry items. Just like with our other log and metric buffers. - since `Map` is [insertion order preserving](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map#description), we apply a FIFO strategy when`drain`ing the trace buckets. This is in line with our [develop spec](https://develop.sentry.dev/sdk/telemetry/telemetry-processor/backend-telemetry-processor/#:~:text=The%20span%20buffer,in%20the%20buffer.) for the telemetry processor but might lead to cases where new traces are dropped by the promise buffer if a lof of concurrently running traces are flushed. I think that's a fine trade off. ref #19119
Lms24 added a commit
that referenced
this pull request
Feb 16, 2026
This PR adds a simple span buffer implementation to be used for buffering streamed spans. Behaviour: - buckets incoming spans by `traceId`, as we must not mix up spans of different traces in one envelope - flushes the entire buffer every 5s by default - flushes the specific trace bucket if the max span limit (1000) is reached. Relay accepts at max. 1000 spans per envelope - computes the DSC when flushing the first span of a trace. This is the latest time we can do it as once we flushed we have to freeze the DSC for Dynamic Sampling consistency - debounces the flush interval whenever we flush - flushes the entire buffer if `Sentry.flush()` is called - shuts down the interval-based flushing when `Sentry.close()` is called - [implicit] Client report generation for dropped envelopes is handled in the transport Methods: - `add` accepts a new span to be enqueued into the buffer - `drain` flushes the entire buffer - `flush(traceId)` flushes a specific traceId bucket. This can be used by e.g. the browser span streaming implementation to flush out the trace of a segment span directly once it ends. Options: - `maxSpanLimit` - allows to configure a 0 < maxSpanLimit < 1000 custom span limit. Useful for testing but we could also expose this to users if we see a need - `flushInterval`- allows to configure a >0 flush interval Limitations/edge cases: - No maximum limit of concurrently buffered traces. I'd tend to accept this for now and see where this leads us in terms of memory pressure but at the end of the day, the interval based flushing, in combination with our promise buffer _should_ avoid an ever-growing map of trace buckets. Happy to change this if reviewers have strong opinions or I'm missing something important! - There's no priority based scheduling relative to other telemetry items. Just like with our other log and metric buffers. - since `Map` is [insertion order preserving](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map#description), we apply a FIFO strategy when`drain`ing the trace buckets. This is in line with our [develop spec](https://develop.sentry.dev/sdk/telemetry/telemetry-processor/backend-telemetry-processor/#:~:text=The%20span%20buffer,in%20the%20buffer.) for the telemetry processor but might lead to cases where new traces are dropped by the promise buffer if a lof of concurrently running traces are flushed. I think that's a fine trade off. ref #19119
Lms24 added a commit
that referenced
this pull request
Mar 2, 2026
This PR adds a simple span buffer implementation to be used for buffering streamed spans. Behaviour: - buckets incoming spans by `traceId`, as we must not mix up spans of different traces in one envelope - flushes the entire buffer every 5s by default - flushes the specific trace bucket if the max span limit (1000) is reached. Relay accepts at max. 1000 spans per envelope - computes the DSC when flushing the first span of a trace. This is the latest time we can do it as once we flushed we have to freeze the DSC for Dynamic Sampling consistency - debounces the flush interval whenever we flush - flushes the entire buffer if `Sentry.flush()` is called - shuts down the interval-based flushing when `Sentry.close()` is called - [implicit] Client report generation for dropped envelopes is handled in the transport Methods: - `add` accepts a new span to be enqueued into the buffer - `drain` flushes the entire buffer - `flush(traceId)` flushes a specific traceId bucket. This can be used by e.g. the browser span streaming implementation to flush out the trace of a segment span directly once it ends. Options: - `maxSpanLimit` - allows to configure a 0 < maxSpanLimit < 1000 custom span limit. Useful for testing but we could also expose this to users if we see a need - `flushInterval`- allows to configure a >0 flush interval Limitations/edge cases: - No maximum limit of concurrently buffered traces. I'd tend to accept this for now and see where this leads us in terms of memory pressure but at the end of the day, the interval based flushing, in combination with our promise buffer _should_ avoid an ever-growing map of trace buckets. Happy to change this if reviewers have strong opinions or I'm missing something important! - There's no priority based scheduling relative to other telemetry items. Just like with our other log and metric buffers. - since `Map` is [insertion order preserving](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map#description), we apply a FIFO strategy when`drain`ing the trace buckets. This is in line with our [develop spec](https://develop.sentry.dev/sdk/telemetry/telemetry-processor/backend-telemetry-processor/#:~:text=The%20span%20buffer,in%20the%20buffer.) for the telemetry processor but might lead to cases where new traces are dropped by the promise buffer if a lof of concurrently running traces are flushed. I think that's a fine trade off. ref #19119
Lms24 added a commit
that referenced
this pull request
Mar 4, 2026
This PR adds a simple span buffer implementation to be used for buffering streamed spans. Behaviour: - buckets incoming spans by `traceId`, as we must not mix up spans of different traces in one envelope - flushes the entire buffer every 5s by default - flushes the specific trace bucket if the max span limit (1000) is reached. Relay accepts at max. 1000 spans per envelope - computes the DSC when flushing the first span of a trace. This is the latest time we can do it as once we flushed we have to freeze the DSC for Dynamic Sampling consistency - debounces the flush interval whenever we flush - flushes the entire buffer if `Sentry.flush()` is called - shuts down the interval-based flushing when `Sentry.close()` is called - [implicit] Client report generation for dropped envelopes is handled in the transport Methods: - `add` accepts a new span to be enqueued into the buffer - `drain` flushes the entire buffer - `flush(traceId)` flushes a specific traceId bucket. This can be used by e.g. the browser span streaming implementation to flush out the trace of a segment span directly once it ends. Options: - `maxSpanLimit` - allows to configure a 0 < maxSpanLimit < 1000 custom span limit. Useful for testing but we could also expose this to users if we see a need - `flushInterval`- allows to configure a >0 flush interval Limitations/edge cases: - No maximum limit of concurrently buffered traces. I'd tend to accept this for now and see where this leads us in terms of memory pressure but at the end of the day, the interval based flushing, in combination with our promise buffer _should_ avoid an ever-growing map of trace buckets. Happy to change this if reviewers have strong opinions or I'm missing something important! - There's no priority based scheduling relative to other telemetry items. Just like with our other log and metric buffers. - since `Map` is [insertion order preserving](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map#description), we apply a FIFO strategy when`drain`ing the trace buckets. This is in line with our [develop spec](https://develop.sentry.dev/sdk/telemetry/telemetry-processor/backend-telemetry-processor/#:~:text=The%20span%20buffer,in%20the%20buffer.) for the telemetry processor but might lead to cases where new traces are dropped by the promise buffer if a lof of concurrently running traces are flushed. I think that's a fine trade off. ref #19119
Lms24 added a commit
that referenced
this pull request
Mar 6, 2026
This PR adds a simple span buffer implementation to be used for buffering streamed spans. Behaviour: - buckets incoming spans by `traceId`, as we must not mix up spans of different traces in one envelope - flushes the entire buffer every 5s by default - flushes the specific trace bucket if the max span limit (1000) is reached. Relay accepts at max. 1000 spans per envelope - computes the DSC when flushing the first span of a trace. This is the latest time we can do it as once we flushed we have to freeze the DSC for Dynamic Sampling consistency - debounces the flush interval whenever we flush - flushes the entire buffer if `Sentry.flush()` is called - shuts down the interval-based flushing when `Sentry.close()` is called - [implicit] Client report generation for dropped envelopes is handled in the transport Methods: - `add` accepts a new span to be enqueued into the buffer - `drain` flushes the entire buffer - `flush(traceId)` flushes a specific traceId bucket. This can be used by e.g. the browser span streaming implementation to flush out the trace of a segment span directly once it ends. Options: - `maxSpanLimit` - allows to configure a 0 < maxSpanLimit < 1000 custom span limit. Useful for testing but we could also expose this to users if we see a need - `flushInterval`- allows to configure a >0 flush interval Limitations/edge cases: - No maximum limit of concurrently buffered traces. I'd tend to accept this for now and see where this leads us in terms of memory pressure but at the end of the day, the interval based flushing, in combination with our promise buffer _should_ avoid an ever-growing map of trace buckets. Happy to change this if reviewers have strong opinions or I'm missing something important! - There's no priority based scheduling relative to other telemetry items. Just like with our other log and metric buffers. - since `Map` is [insertion order preserving](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map#description), we apply a FIFO strategy when`drain`ing the trace buckets. This is in line with our [develop spec](https://develop.sentry.dev/sdk/telemetry/telemetry-processor/backend-telemetry-processor/#:~:text=The%20span%20buffer,in%20the%20buffer.) for the telemetry processor but might lead to cases where new traces are dropped by the promise buffer if a lof of concurrently running traces are flushed. I think that's a fine trade off. ref #19119
Lms24 added a commit
that referenced
this pull request
Mar 9, 2026
This PR adds a simple span buffer implementation to be used for buffering streamed spans. Behaviour: - buckets incoming spans by `traceId`, as we must not mix up spans of different traces in one envelope - flushes the entire buffer every 5s by default - flushes the specific trace bucket if the max span limit (1000) is reached. Relay accepts at max. 1000 spans per envelope - computes the DSC when flushing the first span of a trace. This is the latest time we can do it as once we flushed we have to freeze the DSC for Dynamic Sampling consistency - debounces the flush interval whenever we flush - flushes the entire buffer if `Sentry.flush()` is called - shuts down the interval-based flushing when `Sentry.close()` is called - [implicit] Client report generation for dropped envelopes is handled in the transport Methods: - `add` accepts a new span to be enqueued into the buffer - `drain` flushes the entire buffer - `flush(traceId)` flushes a specific traceId bucket. This can be used by e.g. the browser span streaming implementation to flush out the trace of a segment span directly once it ends. Options: - `maxSpanLimit` - allows to configure a 0 < maxSpanLimit < 1000 custom span limit. Useful for testing but we could also expose this to users if we see a need - `flushInterval`- allows to configure a >0 flush interval Limitations/edge cases: - No maximum limit of concurrently buffered traces. I'd tend to accept this for now and see where this leads us in terms of memory pressure but at the end of the day, the interval based flushing, in combination with our promise buffer _should_ avoid an ever-growing map of trace buckets. Happy to change this if reviewers have strong opinions or I'm missing something important! - There's no priority based scheduling relative to other telemetry items. Just like with our other log and metric buffers. - since `Map` is [insertion order preserving](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map#description), we apply a FIFO strategy when`drain`ing the trace buckets. This is in line with our [develop spec](https://develop.sentry.dev/sdk/telemetry/telemetry-processor/backend-telemetry-processor/#:~:text=The%20span%20buffer,in%20the%20buffer.) for the telemetry processor but might lead to cases where new traces are dropped by the promise buffer if a lof of concurrently running traces are flushed. I think that's a fine trade off. ref #19119
Lms24 added a commit
that referenced
this pull request
Mar 10, 2026
This PR adds a simple span buffer implementation to be used for buffering streamed spans. Behaviour: - buckets incoming spans by `traceId`, as we must not mix up spans of different traces in one envelope - flushes the entire buffer every 5s by default - flushes the specific trace bucket if the max span limit (1000) is reached. Relay accepts at max. 1000 spans per envelope - computes the DSC when flushing the first span of a trace. This is the latest time we can do it as once we flushed we have to freeze the DSC for Dynamic Sampling consistency - debounces the flush interval whenever we flush - flushes the entire buffer if `Sentry.flush()` is called - shuts down the interval-based flushing when `Sentry.close()` is called - [implicit] Client report generation for dropped envelopes is handled in the transport Methods: - `add` accepts a new span to be enqueued into the buffer - `drain` flushes the entire buffer - `flush(traceId)` flushes a specific traceId bucket. This can be used by e.g. the browser span streaming implementation to flush out the trace of a segment span directly once it ends. Options: - `maxSpanLimit` - allows to configure a 0 < maxSpanLimit < 1000 custom span limit. Useful for testing but we could also expose this to users if we see a need - `flushInterval`- allows to configure a >0 flush interval Limitations/edge cases: - No maximum limit of concurrently buffered traces. I'd tend to accept this for now and see where this leads us in terms of memory pressure but at the end of the day, the interval based flushing, in combination with our promise buffer _should_ avoid an ever-growing map of trace buckets. Happy to change this if reviewers have strong opinions or I'm missing something important! - There's no priority based scheduling relative to other telemetry items. Just like with our other log and metric buffers. - since `Map` is [insertion order preserving](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map#description), we apply a FIFO strategy when`drain`ing the trace buckets. This is in line with our [develop spec](https://develop.sentry.dev/sdk/telemetry/telemetry-processor/backend-telemetry-processor/#:~:text=The%20span%20buffer,in%20the%20buffer.) for the telemetry processor but might lead to cases where new traces are dropped by the promise buffer if a lof of concurrently running traces are flushed. I think that's a fine trade off. ref #19119
Lms24 added a commit
that referenced
this pull request
Mar 13, 2026
This PR adds a simple span buffer implementation to be used for buffering streamed spans. Behaviour: - buckets incoming spans by `traceId`, as we must not mix up spans of different traces in one envelope - flushes the entire buffer every 5s by default - flushes the specific trace bucket if the max span limit (1000) is reached. Relay accepts at max. 1000 spans per envelope - computes the DSC when flushing the first span of a trace. This is the latest time we can do it as once we flushed we have to freeze the DSC for Dynamic Sampling consistency - debounces the flush interval whenever we flush - flushes the entire buffer if `Sentry.flush()` is called - shuts down the interval-based flushing when `Sentry.close()` is called - [implicit] Client report generation for dropped envelopes is handled in the transport Methods: - `add` accepts a new span to be enqueued into the buffer - `drain` flushes the entire buffer - `flush(traceId)` flushes a specific traceId bucket. This can be used by e.g. the browser span streaming implementation to flush out the trace of a segment span directly once it ends. Options: - `maxSpanLimit` - allows to configure a 0 < maxSpanLimit < 1000 custom span limit. Useful for testing but we could also expose this to users if we see a need - `flushInterval`- allows to configure a >0 flush interval Limitations/edge cases: - No maximum limit of concurrently buffered traces. I'd tend to accept this for now and see where this leads us in terms of memory pressure but at the end of the day, the interval based flushing, in combination with our promise buffer _should_ avoid an ever-growing map of trace buckets. Happy to change this if reviewers have strong opinions or I'm missing something important! - There's no priority based scheduling relative to other telemetry items. Just like with our other log and metric buffers. - since `Map` is [insertion order preserving](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map#description), we apply a FIFO strategy when`drain`ing the trace buckets. This is in line with our [develop spec](https://develop.sentry.dev/sdk/telemetry/telemetry-processor/backend-telemetry-processor/#:~:text=The%20span%20buffer,in%20the%20buffer.) for the telemetry processor but might lead to cases where new traces are dropped by the promise buffer if a lof of concurrently running traces are flushed. I think that's a fine trade off. ref #19119
Lms24 added a commit
that referenced
this pull request
Mar 18, 2026
This PR adds a simple span buffer implementation to be used for buffering streamed spans. Behaviour: - buckets incoming spans by `traceId`, as we must not mix up spans of different traces in one envelope - flushes the entire buffer every 5s by default - flushes the specific trace bucket if the max span limit (1000) is reached. Relay accepts at max. 1000 spans per envelope - computes the DSC when flushing the first span of a trace. This is the latest time we can do it as once we flushed we have to freeze the DSC for Dynamic Sampling consistency - debounces the flush interval whenever we flush - flushes the entire buffer if `Sentry.flush()` is called - shuts down the interval-based flushing when `Sentry.close()` is called - [implicit] Client report generation for dropped envelopes is handled in the transport Methods: - `add` accepts a new span to be enqueued into the buffer - `drain` flushes the entire buffer - `flush(traceId)` flushes a specific traceId bucket. This can be used by e.g. the browser span streaming implementation to flush out the trace of a segment span directly once it ends. Options: - `maxSpanLimit` - allows to configure a 0 < maxSpanLimit < 1000 custom span limit. Useful for testing but we could also expose this to users if we see a need - `flushInterval`- allows to configure a >0 flush interval Limitations/edge cases: - No maximum limit of concurrently buffered traces. I'd tend to accept this for now and see where this leads us in terms of memory pressure but at the end of the day, the interval based flushing, in combination with our promise buffer _should_ avoid an ever-growing map of trace buckets. Happy to change this if reviewers have strong opinions or I'm missing something important! - There's no priority based scheduling relative to other telemetry items. Just like with our other log and metric buffers. - since `Map` is [insertion order preserving](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map#description), we apply a FIFO strategy when`drain`ing the trace buckets. This is in line with our [develop spec](https://develop.sentry.dev/sdk/telemetry/telemetry-processor/backend-telemetry-processor/#:~:text=The%20span%20buffer,in%20the%20buffer.) for the telemetry processor but might lead to cases where new traces are dropped by the promise buffer if a lof of concurrently running traces are flushed. I think that's a fine trade off. ref #19119
logaretm pushed a commit
that referenced
this pull request
Mar 18, 2026
This PR adds a simple span buffer implementation to be used for buffering streamed spans. Behaviour: - buckets incoming spans by `traceId`, as we must not mix up spans of different traces in one envelope - flushes the entire buffer every 5s by default - flushes the specific trace bucket if the max span limit (1000) is reached. Relay accepts at max. 1000 spans per envelope - computes the DSC when flushing the first span of a trace. This is the latest time we can do it as once we flushed we have to freeze the DSC for Dynamic Sampling consistency - debounces the flush interval whenever we flush - flushes the entire buffer if `Sentry.flush()` is called - shuts down the interval-based flushing when `Sentry.close()` is called - [implicit] Client report generation for dropped envelopes is handled in the transport Methods: - `add` accepts a new span to be enqueued into the buffer - `drain` flushes the entire buffer - `flush(traceId)` flushes a specific traceId bucket. This can be used by e.g. the browser span streaming implementation to flush out the trace of a segment span directly once it ends. Options: - `maxSpanLimit` - allows to configure a 0 < maxSpanLimit < 1000 custom span limit. Useful for testing but we could also expose this to users if we see a need - `flushInterval`- allows to configure a >0 flush interval Limitations/edge cases: - No maximum limit of concurrently buffered traces. I'd tend to accept this for now and see where this leads us in terms of memory pressure but at the end of the day, the interval based flushing, in combination with our promise buffer _should_ avoid an ever-growing map of trace buckets. Happy to change this if reviewers have strong opinions or I'm missing something important! - There's no priority based scheduling relative to other telemetry items. Just like with our other log and metric buffers. - since `Map` is [insertion order preserving](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map#description), we apply a FIFO strategy when`drain`ing the trace buckets. This is in line with our [develop spec](https://develop.sentry.dev/sdk/telemetry/telemetry-processor/backend-telemetry-processor/#:~:text=The%20span%20buffer,in%20the%20buffer.) for the telemetry processor but might lead to cases where new traces are dropped by the promise buffer if a lof of concurrently running traces are flushed. I think that's a fine trade off. ref #19119
Lms24 added a commit
that referenced
this pull request
Mar 23, 2026
This PR adds a simple span buffer implementation to be used for buffering streamed spans. Behaviour: - buckets incoming spans by `traceId`, as we must not mix up spans of different traces in one envelope - flushes the entire buffer every 5s by default - flushes the specific trace bucket if the max span limit (1000) is reached. Relay accepts at max. 1000 spans per envelope - computes the DSC when flushing the first span of a trace. This is the latest time we can do it as once we flushed we have to freeze the DSC for Dynamic Sampling consistency - debounces the flush interval whenever we flush - flushes the entire buffer if `Sentry.flush()` is called - shuts down the interval-based flushing when `Sentry.close()` is called - [implicit] Client report generation for dropped envelopes is handled in the transport Methods: - `add` accepts a new span to be enqueued into the buffer - `drain` flushes the entire buffer - `flush(traceId)` flushes a specific traceId bucket. This can be used by e.g. the browser span streaming implementation to flush out the trace of a segment span directly once it ends. Options: - `maxSpanLimit` - allows to configure a 0 < maxSpanLimit < 1000 custom span limit. Useful for testing but we could also expose this to users if we see a need - `flushInterval`- allows to configure a >0 flush interval Limitations/edge cases: - No maximum limit of concurrently buffered traces. I'd tend to accept this for now and see where this leads us in terms of memory pressure but at the end of the day, the interval based flushing, in combination with our promise buffer _should_ avoid an ever-growing map of trace buckets. Happy to change this if reviewers have strong opinions or I'm missing something important! - There's no priority based scheduling relative to other telemetry items. Just like with our other log and metric buffers. - since `Map` is [insertion order preserving](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map#description), we apply a FIFO strategy when`drain`ing the trace buckets. This is in line with our [develop spec](https://develop.sentry.dev/sdk/telemetry/telemetry-processor/backend-telemetry-processor/#:~:text=The%20span%20buffer,in%20the%20buffer.) for the telemetry processor but might lead to cases where new traces are dropped by the promise buffer if a lof of concurrently running traces are flushed. I think that's a fine trade off. ref #19119
Lms24 added a commit
that referenced
this pull request
Mar 30, 2026
This PR adds a simple span buffer implementation to be used for buffering streamed spans. Behaviour: - buckets incoming spans by `traceId`, as we must not mix up spans of different traces in one envelope - flushes the entire buffer every 5s by default - flushes the specific trace bucket if the max span limit (1000) is reached. Relay accepts at max. 1000 spans per envelope - computes the DSC when flushing the first span of a trace. This is the latest time we can do it as once we flushed we have to freeze the DSC for Dynamic Sampling consistency - debounces the flush interval whenever we flush - flushes the entire buffer if `Sentry.flush()` is called - shuts down the interval-based flushing when `Sentry.close()` is called - [implicit] Client report generation for dropped envelopes is handled in the transport Methods: - `add` accepts a new span to be enqueued into the buffer - `drain` flushes the entire buffer - `flush(traceId)` flushes a specific traceId bucket. This can be used by e.g. the browser span streaming implementation to flush out the trace of a segment span directly once it ends. Options: - `maxSpanLimit` - allows to configure a 0 < maxSpanLimit < 1000 custom span limit. Useful for testing but we could also expose this to users if we see a need - `flushInterval`- allows to configure a >0 flush interval Limitations/edge cases: - No maximum limit of concurrently buffered traces. I'd tend to accept this for now and see where this leads us in terms of memory pressure but at the end of the day, the interval based flushing, in combination with our promise buffer _should_ avoid an ever-growing map of trace buckets. Happy to change this if reviewers have strong opinions or I'm missing something important! - There's no priority based scheduling relative to other telemetry items. Just like with our other log and metric buffers. - since `Map` is [insertion order preserving](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map#description), we apply a FIFO strategy when`drain`ing the trace buckets. This is in line with our [develop spec](https://develop.sentry.dev/sdk/telemetry/telemetry-processor/backend-telemetry-processor/#:~:text=The%20span%20buffer,in%20the%20buffer.) for the telemetry processor but might lead to cases where new traces are dropped by the promise buffer if a lof of concurrently running traces are flushed. I think that's a fine trade off. ref #19119
Lms24 added a commit
that referenced
this pull request
Apr 2, 2026
This PR adds a simple span buffer implementation to be used for buffering streamed spans. Behaviour: - buckets incoming spans by `traceId`, as we must not mix up spans of different traces in one envelope - flushes the entire buffer every 5s by default - flushes the specific trace bucket if the max span limit (1000) is reached. Relay accepts at max. 1000 spans per envelope - computes the DSC when flushing the first span of a trace. This is the latest time we can do it as once we flushed we have to freeze the DSC for Dynamic Sampling consistency - debounces the flush interval whenever we flush - flushes the entire buffer if `Sentry.flush()` is called - shuts down the interval-based flushing when `Sentry.close()` is called - [implicit] Client report generation for dropped envelopes is handled in the transport Methods: - `add` accepts a new span to be enqueued into the buffer - `drain` flushes the entire buffer - `flush(traceId)` flushes a specific traceId bucket. This can be used by e.g. the browser span streaming implementation to flush out the trace of a segment span directly once it ends. Options: - `maxSpanLimit` - allows to configure a 0 < maxSpanLimit < 1000 custom span limit. Useful for testing but we could also expose this to users if we see a need - `flushInterval`- allows to configure a >0 flush interval Limitations/edge cases: - No maximum limit of concurrently buffered traces. I'd tend to accept this for now and see where this leads us in terms of memory pressure but at the end of the day, the interval based flushing, in combination with our promise buffer _should_ avoid an ever-growing map of trace buckets. Happy to change this if reviewers have strong opinions or I'm missing something important! - There's no priority based scheduling relative to other telemetry items. Just like with our other log and metric buffers. - since `Map` is [insertion order preserving](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map#description), we apply a FIFO strategy when`drain`ing the trace buckets. This is in line with our [develop spec](https://develop.sentry.dev/sdk/telemetry/telemetry-processor/backend-telemetry-processor/#:~:text=The%20span%20buffer,in%20the%20buffer.) for the telemetry processor but might lead to cases where new traces are dropped by the promise buffer if a lof of concurrently running traces are flushed. I think that's a fine trade off. ref #19119
Lms24 added a commit
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this pull request
Apr 8, 2026
This PR adds a simple span buffer implementation to be used for buffering streamed spans. Behaviour: - buckets incoming spans by `traceId`, as we must not mix up spans of different traces in one envelope - flushes the entire buffer every 5s by default - flushes the specific trace bucket if the max span limit (1000) is reached. Relay accepts at max. 1000 spans per envelope - computes the DSC when flushing the first span of a trace. This is the latest time we can do it as once we flushed we have to freeze the DSC for Dynamic Sampling consistency - debounces the flush interval whenever we flush - flushes the entire buffer if `Sentry.flush()` is called - shuts down the interval-based flushing when `Sentry.close()` is called - [implicit] Client report generation for dropped envelopes is handled in the transport Methods: - `add` accepts a new span to be enqueued into the buffer - `drain` flushes the entire buffer - `flush(traceId)` flushes a specific traceId bucket. This can be used by e.g. the browser span streaming implementation to flush out the trace of a segment span directly once it ends. Options: - `maxSpanLimit` - allows to configure a 0 < maxSpanLimit < 1000 custom span limit. Useful for testing but we could also expose this to users if we see a need - `flushInterval`- allows to configure a >0 flush interval Limitations/edge cases: - No maximum limit of concurrently buffered traces. I'd tend to accept this for now and see where this leads us in terms of memory pressure but at the end of the day, the interval based flushing, in combination with our promise buffer _should_ avoid an ever-growing map of trace buckets. Happy to change this if reviewers have strong opinions or I'm missing something important! - There's no priority based scheduling relative to other telemetry items. Just like with our other log and metric buffers. - since `Map` is [insertion order preserving](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map#description), we apply a FIFO strategy when`drain`ing the trace buckets. This is in line with our [develop spec](https://develop.sentry.dev/sdk/telemetry/telemetry-processor/backend-telemetry-processor/#:~:text=The%20span%20buffer,in%20the%20buffer.) for the telemetry processor but might lead to cases where new traces are dropped by the promise buffer if a lof of concurrently running traces are flushed. I think that's a fine trade off. ref #19119
Lms24 added a commit
that referenced
this pull request
Apr 9, 2026
This PR adds a simple span buffer implementation to be used for buffering streamed spans. Behaviour: - buckets incoming spans by `traceId`, as we must not mix up spans of different traces in one envelope - flushes the entire buffer every 5s by default - flushes the specific trace bucket if the max span limit (1000) is reached. Relay accepts at max. 1000 spans per envelope - computes the DSC when flushing the first span of a trace. This is the latest time we can do it as once we flushed we have to freeze the DSC for Dynamic Sampling consistency - debounces the flush interval whenever we flush - flushes the entire buffer if `Sentry.flush()` is called - shuts down the interval-based flushing when `Sentry.close()` is called - [implicit] Client report generation for dropped envelopes is handled in the transport Methods: - `add` accepts a new span to be enqueued into the buffer - `drain` flushes the entire buffer - `flush(traceId)` flushes a specific traceId bucket. This can be used by e.g. the browser span streaming implementation to flush out the trace of a segment span directly once it ends. Options: - `maxSpanLimit` - allows to configure a 0 < maxSpanLimit < 1000 custom span limit. Useful for testing but we could also expose this to users if we see a need - `flushInterval`- allows to configure a >0 flush interval Limitations/edge cases: - No maximum limit of concurrently buffered traces. I'd tend to accept this for now and see where this leads us in terms of memory pressure but at the end of the day, the interval based flushing, in combination with our promise buffer _should_ avoid an ever-growing map of trace buckets. Happy to change this if reviewers have strong opinions or I'm missing something important! - There's no priority based scheduling relative to other telemetry items. Just like with our other log and metric buffers. - since `Map` is [insertion order preserving](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map#description), we apply a FIFO strategy when`drain`ing the trace buckets. This is in line with our [develop spec](https://develop.sentry.dev/sdk/telemetry/telemetry-processor/backend-telemetry-processor/#:~:text=The%20span%20buffer,in%20the%20buffer.) for the telemetry processor but might lead to cases where new traces are dropped by the promise buffer if a lof of concurrently running traces are flushed. I think that's a fine trade off. ref #19119
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This PR adds a simple span buffer implementation to be used for buffering streamed spans.
Behaviour:
traceId, as we must not mix up spans of different traces in one envelopeSentry.flush()is calledSentry.close()is calledMethods:
addaccepts a new span to be enqueued into the bufferdrainflushes the entire bufferflush(traceId)flushes a specific traceId bucket. This can be used by e.g. the browser span streaming implementation to flush out the trace of a segment span directly once it ends.Options:
maxSpanLimit- allows to configure a 0 < maxSpanLimit < 1000 custom span limit. Useful for testing but we could also expose this to users if we see a needflushInterval- allows to configure a >0 flush intervalLimitations/edge cases:
Mapis insertion order preserving, we apply a FIFO strategy whendraining the trace buckets. This is in line with our develop spec for the telemetry processor but might lead to cases where new traces are dropped by the promise buffer if a lof of concurrently running traces are flushed. I think that's a fine trade off.ref #19119