Metrics flush timer should use .unref() to not block process exit #19171

Closed
#19174
Closed
Metrics flush timer should use .unref() to not block process exit#19171
#19174
Assignees
JPeer264
Labels
Bug

Description

@BYK
BYK
opened on Feb 4, 2026

Problem

The metrics flush timer created in setupWeightBasedFlushing() (in packages/core/src/client.ts) does not call .unref() on the setTimeout timer. This causes the Node.js event loop to stay alive for up to 5 seconds after the main work is complete, preventing CLI tools and short-lived processes from exiting promptly.

Current behavior

// packages/core/src/client.ts, setupWeightBasedFlushing()flushTimeout=setTimeout(()=>{flushFn(client);},DEFAULT_FLUSH_INTERVAL);// 5000ms

This timer keeps the process alive even after client.flush() is called (though flush() does clear the timer via the flushHook event, the timer may be recreated if metrics are captured during flushing).

Expected behavior

The timer should use .unref() so it doesn't prevent the process from exiting:

flushTimeout=setTimeout(()=>{flushFn(client);},DEFAULT_FLUSH_INTERVAL);if(typeofflushTimeout!=='number'&&flushTimeout.unref){flushTimeout.unref();}

This pattern is already used elsewhere in the SDK:

  • client.ts line ~655: _isClientDoneProcessing()
  • promisebuffer.ts: drain timeout

Impact

This affects any short-lived Node.js process using Sentry metrics:

  • CLI tools
  • Serverless functions
  • Scripts

Workaround

We're currently patching the SDK in our project: https://github.com/getsentry/cli/blob/main/patches/%40sentry%2Fcore%4010.38.0.patch

Environment

  • @sentry/bun / @sentry/node: 10.38.0
  • Node.js / Bun: All versions

Activity

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    , 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Add copy buttons to all 
     blocks\n(function() {\n function addCopyButtons() {\n document.querySelectorAll('pre code').forEach(function(codeBlock) {\n if (codeBlock.parentElement.hasAttribute('data-copy-added')) return;\n codeBlock.parentElement.setAttribute('data-copy-added', 'true');\n \n var btn = document.createElement('button');\n btn.textContent = 'Copy';\n btn.style.cssText = 'position:absolute;top:4px;right:4px;padding:2px 8px;font-size:11px;background:#4ecdc4;border:none;border-radius:4px;color:#1a1a2e;cursor:pointer;opacity:0.7;transition:opacity 0.2s;';\n btn.onmouseover = function() { this.style.opacity = '1'; };\n btn.onmouseout = function() { this.style.opacity = '0.7'; };\n btn.onclick = function() {\n navigator.clipboard.writeText(codeBlock.textContent).then(function() {\n btn.textContent = 'Copied!';\n setTimeout(function() { btn.textContent = 'Copy'; }, 1500);\n });\n };\n codeBlock.parentElement.style.position = 'relative';\n codeBlock.parentElement.appendChild(btn);\n });\n }\n \n addCopyButtons();\n \n // Re-run on dynamic content\n var observer = new MutationObserver(addCopyButtons);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Add Copy Buttons to Code Blocks");
}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
(function(){
try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '

    Skip to content
    Metrics flush timer should use .unref() to not block process exit #19171
    Closed
    #19174
    Closed
    Metrics flush timer should use .unref() to not block process exit#19171
    #19174
    Assignees
    JPeer264
    Labels
    Bug
    Description
    @BYK
    BYK
    opened on Feb 4, 2026
    Problem
    The metrics flush timer created in setupWeightBasedFlushing() (in packages/core/src/client.ts) does not call .unref() on the setTimeout timer. This causes the Node.js event loop to stay alive for up to 5 seconds after the main work is complete, preventing CLI tools and short-lived processes from exiting promptly.
    Current behavior
    // packages/core/src/client.ts, setupWeightBasedFlushing()flushTimeout=setTimeout(()=>{flushFn(client);},DEFAULT_FLUSH_INTERVAL);// 5000ms
    This timer keeps the process alive even after client.flush() is called (though flush() does clear the timer via the flushHook event, the timer may be recreated if metrics are captured during flushing).
    Expected behavior
    The timer should use .unref() so it doesn't prevent the process from exiting:
    flushTimeout=setTimeout(()=>{flushFn(client);},DEFAULT_FLUSH_INTERVAL);if(typeofflushTimeout!=='number'&&flushTimeout.unref){flushTimeout.unref();}
    This pattern is already used elsewhere in the SDK:
    • client.ts line ~655: _isClientDoneProcessing()
    • promisebuffer.ts: drain timeout
    Impact
    This affects any short-lived Node.js process using Sentry metrics:
    • CLI tools
    • Serverless functions
    • Scripts
    Workaround
    We're currently patching the SDK in our project: https://github.com/getsentry/cli/blob/main/patches/%40sentry%2Fcore%4010.38.0.patch
    Environment
    • @sentry/bun / @sentry/node: 10.38.0
    • Node.js / Bun: All versions
    Activity
    Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
    Metadata
    Metadata
    Assignees
    Labels
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    No projects
      Milestone
      No milestone
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      None yet
      Development
      No branches or pull requests
      Issue actions
      
, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Force GitHub README to respect dark mode\n(function() {\n var style = document.createElement('style');\n style.textContent = '\n .markdown-body {\n color-scheme: dark light;\n }\n .markdown-body pre { background: #161b22 !important; }\n .markdown-body code { background: rgba(110, 118, 129, 0.4) !important; }\n .markdown-body table th, .markdown-body table td { border-color: #30363d !important; }\n .markdown-body img { background: #0d1117; }\n .markdown-body blockquote { border-left-color: #8b949e; }\n .markdown-body hr { border-color: #30363d; }\n ';\n document.head.appendChild(style);\n})();", "GitHub Dark Mode README Fix");
}
} catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

      Skip to content
      Metrics flush timer should use .unref() to not block process exit #19171
      Closed
      #19174
      Closed
      Metrics flush timer should use .unref() to not block process exit#19171
      #19174
      Assignees
      JPeer264
      Labels
      Bug
      Description
      @BYK
      BYK
      opened on Feb 4, 2026
      Problem
      The metrics flush timer created in setupWeightBasedFlushing() (in packages/core/src/client.ts) does not call .unref() on the setTimeout timer. This causes the Node.js event loop to stay alive for up to 5 seconds after the main work is complete, preventing CLI tools and short-lived processes from exiting promptly.
      Current behavior
      // packages/core/src/client.ts, setupWeightBasedFlushing()flushTimeout=setTimeout(()=>{flushFn(client);},DEFAULT_FLUSH_INTERVAL);// 5000ms
      This timer keeps the process alive even after client.flush() is called (though flush() does clear the timer via the flushHook event, the timer may be recreated if metrics are captured during flushing).
      Expected behavior
      The timer should use .unref() so it doesn't prevent the process from exiting:
      flushTimeout=setTimeout(()=>{flushFn(client);},DEFAULT_FLUSH_INTERVAL);if(typeofflushTimeout!=='number'&&flushTimeout.unref){flushTimeout.unref();}
      This pattern is already used elsewhere in the SDK:
      • client.ts line ~655: _isClientDoneProcessing()
      • promisebuffer.ts: drain timeout
      Impact
      This affects any short-lived Node.js process using Sentry metrics:
      • CLI tools
      • Serverless functions
      • Scripts
      Workaround
      We're currently patching the SDK in our project: https://github.com/getsentry/cli/blob/main/patches/%40sentry%2Fcore%4010.38.0.patch
      Environment
      • @sentry/bun / @sentry/node: 10.38.0
      • Node.js / Bun: All versions
      Activity
      Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
      Metadata
      Metadata
      Assignees
      Labels
      Bug
      Projects
      No projects
        Milestone
        No milestone
        Relationships
        None yet
        Development
        No branches or pull requests
        Issue actions
        
, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Highlight search terms from Google/DuckDuckGo/Bing referrer\n(function() {\n var ref = document.referrer;\n var terms = [];\n \n if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {\n var url = new URL(ref);\n var q = url.searchParams.get('q') || url.searchParams.get('p');\n if (q) {\n terms = q.split(/\\s+/).filter(function(t) { return t.length > 2; });\n }\n }\n \n if (terms.length === 0) return;\n \n var style = document.createElement('style');\n style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';\n document.head.appendChild(style);\n \n function highlight(node) {\n if (node.nodeType === 3) { // text node\n var text = node.textContent;\n var found = false;\n terms.forEach(function(term) {\n var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\\]\\\\]/g, '\\\\') + ')', 'gi');\n if (regex.test(text)) {\n found = true;\n var frag = document.createDocumentFragment();\n var parts = text.split(regex);\n parts.forEach(function(part, i) {\n if (i % 2 === 0) {\n frag.appendChild(document.createTextNode(part));\n } else {\n var span = document.createElement('span');\n span.className = 'userscript-highlight';\n span.textContent = part;\n frag.appendChild(span);\n }\n });\n node.parentNode.replaceChild(frag, node);\n }\n });\n } else if (node.nodeType === 1 && node.childNodes) { // element\n var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];\n if (!skipTags.includes(node.tagName)) {\n Array.from(node.childNodes).forEach(highlight);\n }\n }\n }\n \n highlight(document.body);\n \n // Re-highlight on dynamic content\n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1 || node.nodeType === 3) highlight(node);\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Highlight Search Terms");
}
} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

        Skip to content
        Metrics flush timer should use .unref() to not block process exit #19171
        Closed
        #19174
        Closed
        Metrics flush timer should use .unref() to not block process exit#19171
        #19174
        Assignees
        JPeer264
        Labels
        Bug
        Description
        @BYK
        BYK
        opened on Feb 4, 2026
        Problem
        The metrics flush timer created in setupWeightBasedFlushing() (in packages/core/src/client.ts) does not call .unref() on the setTimeout timer. This causes the Node.js event loop to stay alive for up to 5 seconds after the main work is complete, preventing CLI tools and short-lived processes from exiting promptly.
        Current behavior
        // packages/core/src/client.ts, setupWeightBasedFlushing()flushTimeout=setTimeout(()=>{flushFn(client);},DEFAULT_FLUSH_INTERVAL);// 5000ms
        This timer keeps the process alive even after client.flush() is called (though flush() does clear the timer via the flushHook event, the timer may be recreated if metrics are captured during flushing).
        Expected behavior
        The timer should use .unref() so it doesn't prevent the process from exiting:
        flushTimeout=setTimeout(()=>{flushFn(client);},DEFAULT_FLUSH_INTERVAL);if(typeofflushTimeout!=='number'&&flushTimeout.unref){flushTimeout.unref();}
        This pattern is already used elsewhere in the SDK:
        • client.ts line ~655: _isClientDoneProcessing()
        • promisebuffer.ts: drain timeout
        Impact
        This affects any short-lived Node.js process using Sentry metrics:
        • CLI tools
        • Serverless functions
        • Scripts
        Workaround
        We're currently patching the SDK in our project: https://github.com/getsentry/cli/blob/main/patches/%40sentry%2Fcore%4010.38.0.patch
        Environment
        • @sentry/bun / @sentry/node: 10.38.0
        • Node.js / Bun: All versions
        Activity
        Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
        Metadata
        Metadata
        Assignees
        Labels
        Bug
        Projects
        No projects
          Milestone
          No milestone
          Relationships
          None yet
          Development
          No branches or pull requests
          Issue actions
          
, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Strip utm_, fbclid, gclid, etc. from all links on page\n(function() {\n var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',\n 'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',\n 'ref', 'ref_src', 'source', 'medium', 'campaign'];\n \n function cleanUrl(url) {\n try {\n var u = new URL(url, window.location.origin);\n var changed = false;\n trackingParams.forEach(function(p) {\n if (u.searchParams.has(p)) {\n u.searchParams.delete(p);\n changed = true;\n }\n });\n return changed ? u.toString() : url;\n } catch (e) {\n return url;\n }\n }\n \n function cleanLinks() {\n document.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n \n cleanLinks();\n \n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1) {\n if (node.tagName === 'A') cleanLinks();\n node.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Remove Tracking Parameters from Links");
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '

          Skip to content
          Metrics flush timer should use .unref() to not block process exit #19171
          Closed
          #19174
          Closed
          Metrics flush timer should use .unref() to not block process exit#19171
          #19174
          Assignees
          JPeer264
          Labels
          Bug
          Description
          @BYK
          BYK
          opened on Feb 4, 2026
          Problem
          The metrics flush timer created in setupWeightBasedFlushing() (in packages/core/src/client.ts) does not call .unref() on the setTimeout timer. This causes the Node.js event loop to stay alive for up to 5 seconds after the main work is complete, preventing CLI tools and short-lived processes from exiting promptly.
          Current behavior
          // packages/core/src/client.ts, setupWeightBasedFlushing()flushTimeout=setTimeout(()=>{flushFn(client);},DEFAULT_FLUSH_INTERVAL);// 5000ms
          This timer keeps the process alive even after client.flush() is called (though flush() does clear the timer via the flushHook event, the timer may be recreated if metrics are captured during flushing).
          Expected behavior
          The timer should use .unref() so it doesn't prevent the process from exiting:
          flushTimeout=setTimeout(()=>{flushFn(client);},DEFAULT_FLUSH_INTERVAL);if(typeofflushTimeout!=='number'&&flushTimeout.unref){flushTimeout.unref();}
          This pattern is already used elsewhere in the SDK:
          • client.ts line ~655: _isClientDoneProcessing()
          • promisebuffer.ts: drain timeout
          Impact
          This affects any short-lived Node.js process using Sentry metrics:
          • CLI tools
          • Serverless functions
          • Scripts
          Workaround
          We're currently patching the SDK in our project: https://github.com/getsentry/cli/blob/main/patches/%40sentry%2Fcore%4010.38.0.patch
          Environment
          • @sentry/bun / @sentry/node: 10.38.0
          • Node.js / Bun: All versions
          Activity
          Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
          Metadata
          Metadata
          Assignees
          Labels
          Bug
          Projects
          No projects
            Milestone
            No milestone
            Relationships
            None yet
            Development
            No branches or pull requests
            Issue actions
            
, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Auto-enable theater mode on YouTube\n(function() {\n function tryTheater() {\n var btn = document.querySelector('button[aria-label=\"Theater mode\"], ytd-player #player button[title=\"Theater mode\"]');\n if (btn && !btn.classList.contains('activated')) {\n btn.click();\n }\n }\n \n // Try immediately\n tryTheater();\n \n // Try after navigation (SPA)\n var lastUrl = location.href;\n setInterval(function() {\n if (location.href !== lastUrl) {\n lastUrl = location.href;\n setTimeout(tryTheater, 500);\n }\n }, 1000);\n \n // Also try on player load\n var observer = new MutationObserver(tryTheater);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "YouTube Theater Mode Default");
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

            Skip to content
            Metrics flush timer should use .unref() to not block process exit #19171
            Closed
            #19174
            Closed
            Metrics flush timer should use .unref() to not block process exit#19171
            #19174
            Assignees
            JPeer264
            Labels
            Bug
            Description
            @BYK
            BYK
            opened on Feb 4, 2026
            Problem
            The metrics flush timer created in setupWeightBasedFlushing() (in packages/core/src/client.ts) does not call .unref() on the setTimeout timer. This causes the Node.js event loop to stay alive for up to 5 seconds after the main work is complete, preventing CLI tools and short-lived processes from exiting promptly.
            Current behavior
            // packages/core/src/client.ts, setupWeightBasedFlushing()flushTimeout=setTimeout(()=>{flushFn(client);},DEFAULT_FLUSH_INTERVAL);// 5000ms
            This timer keeps the process alive even after client.flush() is called (though flush() does clear the timer via the flushHook event, the timer may be recreated if metrics are captured during flushing).
            Expected behavior
            The timer should use .unref() so it doesn't prevent the process from exiting:
            flushTimeout=setTimeout(()=>{flushFn(client);},DEFAULT_FLUSH_INTERVAL);if(typeofflushTimeout!=='number'&&flushTimeout.unref){flushTimeout.unref();}
            This pattern is already used elsewhere in the SDK:
            • client.ts line ~655: _isClientDoneProcessing()
            • promisebuffer.ts: drain timeout
            Impact
            This affects any short-lived Node.js process using Sentry metrics:
            • CLI tools
            • Serverless functions
            • Scripts
            Workaround
            We're currently patching the SDK in our project: https://github.com/getsentry/cli/blob/main/patches/%40sentry%2Fcore%4010.38.0.patch
            Environment
            • @sentry/bun / @sentry/node: 10.38.0
            • Node.js / Bun: All versions
            Activity
            Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
            Metadata
            Metadata
            Assignees
            Labels
            Bug
            Projects
            No projects
              Milestone
              No milestone
              Relationships
              None yet
              Development
              No branches or pull requests
              Issue actions
              
, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Remove or un-stick sticky/fixed headers that block content\n(function() {\n function unstick() {\n document.querySelectorAll('header, nav, [role=\"banner\"], .header, .navbar, .sticky, .fixed-top, [style*=\"position: fixed\"], [style*=\"position:sticky\"]').forEach(function(el) {\n if (el.style.position === 'fixed' || el.style.position === 'sticky' || \n getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {\n el.style.position = 'static';\n el.style.top = 'auto';\n el.style.zIndex = 'auto';\n }\n });\n }\n \n unstick();\n \n var observer = new MutationObserver(unstick);\n observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });\n})();", "Kill Sticky Headers");
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

              Skip to content
              Metrics flush timer should use .unref() to not block process exit #19171
              Closed
              #19174
              Closed
              Metrics flush timer should use .unref() to not block process exit#19171
              #19174
              Assignees
              JPeer264
              Labels
              Bug
              Description
              @BYK
              BYK
              opened on Feb 4, 2026
              Problem
              The metrics flush timer created in setupWeightBasedFlushing() (in packages/core/src/client.ts) does not call .unref() on the setTimeout timer. This causes the Node.js event loop to stay alive for up to 5 seconds after the main work is complete, preventing CLI tools and short-lived processes from exiting promptly.
              Current behavior
              // packages/core/src/client.ts, setupWeightBasedFlushing()flushTimeout=setTimeout(()=>{flushFn(client);},DEFAULT_FLUSH_INTERVAL);// 5000ms
              This timer keeps the process alive even after client.flush() is called (though flush() does clear the timer via the flushHook event, the timer may be recreated if metrics are captured during flushing).
              Expected behavior
              The timer should use .unref() so it doesn't prevent the process from exiting:
              flushTimeout=setTimeout(()=>{flushFn(client);},DEFAULT_FLUSH_INTERVAL);if(typeofflushTimeout!=='number'&&flushTimeout.unref){flushTimeout.unref();}
              This pattern is already used elsewhere in the SDK:
              • client.ts line ~655: _isClientDoneProcessing()
              • promisebuffer.ts: drain timeout
              Impact
              This affects any short-lived Node.js process using Sentry metrics:
              • CLI tools
              • Serverless functions
              • Scripts
              Workaround
              We're currently patching the SDK in our project: https://github.com/getsentry/cli/blob/main/patches/%40sentry%2Fcore%4010.38.0.patch
              Environment
              • @sentry/bun / @sentry/node: 10.38.0
              • Node.js / Bun: All versions
              Activity
              Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
              Metadata
              Metadata
              Assignees
              Labels
              Bug
              Projects
              No projects
                Milestone
                No milestone
                Relationships
                None yet
                Development
                No branches or pull requests
                Issue actions
                
, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Universal Dark Mode - works on any site\n(function() {\n var enabled = true;\n \n function applyDarkMode() {\n if (!enabled) return;\n \n // Create style element if it doesn't exist\n var style = document.getElementById('universal-dark-mode-style');\n if (!style) {\n style = document.createElement('style');\n style.id = 'universal-dark-mode-style';\n document.head.appendChild(style);\n }\n \n // Dark mode CSS - inverts colors but preserves images/video\n style.textContent = '\n /* Invert everything except media */\n html {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #1a1a2e !important;\n }\n \n /* Restore images, videos, iframes, canvas */\n img, video, iframe, canvas, svg, picture, [style*=\"background-image\"] {\n filter: invert(1) hue-rotate(180deg) !important;\n }\n \n /* Preserve specific elements that should not be inverted */\n .no-dark-mode, .no-dark-mode *,\n [data-theme=\"light\"], [data-theme=\"light\"],\n .ace_editor, .ace_editor *,\n .CodeMirror, .CodeMirror *,\n .monaco-editor, .monaco-editor *,\n .markdown-body pre, .markdown-body pre *,\n .highlight, .highlight *,\n pre code, pre code * {\n filter: none !important;\n }\n \n /* Fix common UI elements */\n .modal, .popup, .dropdown-menu, .tooltip, .popover {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #2d2d44 !important;\n border-color: #444 !important;\n }\n \n /* Scrollbars */\n ::-webkit-scrollbar { background: #1a1a2e !important; }\n ::-webkit-scrollbar-thumb { background: #444 !important; }\n ::-webkit-scrollbar-thumb:hover { background: #555 !important; }\n \n /* Selection */\n ::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ';\n }\n \n function removeDarkMode() {\n var style = document.getElementById('universal-dark-mode-style');\n if (style) style.remove();\n }\n \n // Toggle with Alt+Shift+D\n document.addEventListener('keydown', function(e) {\n if (e.altKey && e.shiftKey && e.key === 'D') {\n e.preventDefault();\n enabled = !enabled;\n if (enabled) {\n applyDarkMode();\n console.log('[Universal Dark Mode] Enabled');\n } else {\n removeDarkMode();\n console.log('[Universal Dark Mode] Disabled');\n }\n }\n });\n \n // Apply on load\n applyDarkMode();\n \n // Re-apply on dynamic content\n var observer = new MutationObserver(function(mutations) {\n if (enabled && !document.getElementById('universal-dark-mode-style')) {\n applyDarkMode();\n }\n });\n observer.observe(document.head, { childList: true });\n \n console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');\n})();", "Universal Dark Mode");
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();

                Skip to content
                Metrics flush timer should use .unref() to not block process exit #19171
                Closed
                #19174
                Closed
                Metrics flush timer should use .unref() to not block process exit#19171
                #19174
                Assignees
                JPeer264
                Labels
                Bug
                Description
                @BYK
                BYK
                opened on Feb 4, 2026
                Problem
                The metrics flush timer created in setupWeightBasedFlushing() (in packages/core/src/client.ts) does not call .unref() on the setTimeout timer. This causes the Node.js event loop to stay alive for up to 5 seconds after the main work is complete, preventing CLI tools and short-lived processes from exiting promptly.
                Current behavior
                // packages/core/src/client.ts, setupWeightBasedFlushing()flushTimeout=setTimeout(()=>{flushFn(client);},DEFAULT_FLUSH_INTERVAL);// 5000ms
                This timer keeps the process alive even after client.flush() is called (though flush() does clear the timer via the flushHook event, the timer may be recreated if metrics are captured during flushing).
                Expected behavior
                The timer should use .unref() so it doesn't prevent the process from exiting:
                flushTimeout=setTimeout(()=>{flushFn(client);},DEFAULT_FLUSH_INTERVAL);if(typeofflushTimeout!=='number'&&flushTimeout.unref){flushTimeout.unref();}
                This pattern is already used elsewhere in the SDK:
                • client.ts line ~655: _isClientDoneProcessing()
                • promisebuffer.ts: drain timeout
                Impact
                This affects any short-lived Node.js process using Sentry metrics:
                • CLI tools
                • Serverless functions
                • Scripts
                Workaround
                We're currently patching the SDK in our project: https://github.com/getsentry/cli/blob/main/patches/%40sentry%2Fcore%4010.38.0.patch
                Environment
                • @sentry/bun / @sentry/node: 10.38.0
                • Node.js / Bun: All versions
                Activity
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