stream/iter: share() does not discard upstream results with "drop-newest" #64416

Closed
#64417
Closed
stream/iter: share() does not discard upstream results with "drop-newest"#64416
#64417
Assignees
trivikr
Labels
streamIssues and PRs related to Node.js streams.

Description

@trivikr
trivikr
opened on Jul 11, 2026

Version

main

Platform

macOS 26.5.2

Subsystem

stream

What steps will reproduce the bug?

import{share}from'node:stream/iter';asyncfunction*source(){for(leti=0;i<4;i++)yield[newTextEncoder().encode(`${i}`)];}constshared=share(source(),{highWaterMark: 2,backpressure: 'drop-newest',});constfast=shared.pull();constslow=shared.pull();constread=async(stream)=>(awaitArray.fromAsync(stream)).flat().map((chunk)=>newTextDecoder().decode(chunk));console.log('fast:',awaitread(fast));console.log('bufferSize:',shared.bufferSize);console.log('slow:',awaitread(slow));

How often does it reproduce? Is there a required condition?

Always

What is the expected behavior? Why is that the expected behavior?

fast: [ '0', '1' ]bufferSize: 2slow: [ '0', '1' ]

Once the two-slot buffer is full, upstream results '2' and '3' are discarded under "drop-newest".
Neither consumer receives them, and the buffer never exceeds highWaterMark.

From §13.2.2 — “Share buffering and backpressure”

With "drop-newest", the upstream pull result is discarded.

What do you see instead?

fast: [ '0', '1', '2', '3' ]bufferSize: 4slow: [ '0', '1', '2', '3' ]

The buffer grows to four entries despite highWaterMark: 2, and the stalled consumer eventually receives every batch

Additional information

No response

Activity

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Metadata

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streamIssues and PRs related to Node.js streams.

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No projects

    Milestone

    No milestone

    Relationships

    None yet

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    No branches or pull requests

    Issue actions

    , '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
    stream/iter: share() does not discard upstream results with "drop-newest" #64416
    Closed
    #64417
    Closed
    stream/iter: share() does not discard upstream results with "drop-newest"#64416
    #64417
    Assignees
    trivikr
    Labels
    streamIssues and PRs related to Node.js streams.
    Description
    @trivikr
    trivikr
    opened on Jul 11, 2026
    Version
    main
    Platform
    macOS 26.5.2

    Subsystem
    stream
    What steps will reproduce the bug?
    import{share}from'node:stream/iter';asyncfunction*source(){for(leti=0;i<4;i++)yield[newTextEncoder().encode(`${i}`)];}constshared=share(source(),{highWaterMark: 2,backpressure: 'drop-newest',});constfast=shared.pull();constslow=shared.pull();constread=async(stream)=>(awaitArray.fromAsync(stream)).flat().map((chunk)=>newTextDecoder().decode(chunk));console.log('fast:',awaitread(fast));console.log('bufferSize:',shared.bufferSize);console.log('slow:',awaitread(slow));
    How often does it reproduce? Is there a required condition?
    Always
    What is the expected behavior? Why is that the expected behavior?
    fast: [ '0', '1' ]bufferSize: 2slow: [ '0', '1' ]
    Once the two-slot buffer is full, upstream results '2' and '3' are discarded under "drop-newest".
    
Neither consumer receives them, and the buffer never exceeds highWaterMark.
    From §13.2.2 — “Share buffering and backpressure”
    With "drop-newest", the upstream pull result is discarded.
    What do you see instead?
    fast: [ '0', '1', '2', '3' ]bufferSize: 4slow: [ '0', '1', '2', '3' ]
    The buffer grows to four entries despite highWaterMark: 2, and the stalled consumer eventually receives every batch
    Additional information
    No response
    Activity
    Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
    Metadata
    Metadata
    Assignees
    Labels
    streamIssues and PRs related to Node.js streams.
    Type
    No type
    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("// 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
      stream/iter: share() does not discard upstream results with "drop-newest" #64416
      Closed
      #64417
      Closed
      stream/iter: share() does not discard upstream results with "drop-newest"#64416
      #64417
      Assignees
      trivikr
      Labels
      streamIssues and PRs related to Node.js streams.
      Description
      @trivikr
      trivikr
      opened on Jul 11, 2026
      Version
      main
      Platform
      macOS 26.5.2

      Subsystem
      stream
      What steps will reproduce the bug?
      import{share}from'node:stream/iter';asyncfunction*source(){for(leti=0;i<4;i++)yield[newTextEncoder().encode(`${i}`)];}constshared=share(source(),{highWaterMark: 2,backpressure: 'drop-newest',});constfast=shared.pull();constslow=shared.pull();constread=async(stream)=>(awaitArray.fromAsync(stream)).flat().map((chunk)=>newTextDecoder().decode(chunk));console.log('fast:',awaitread(fast));console.log('bufferSize:',shared.bufferSize);console.log('slow:',awaitread(slow));
      How often does it reproduce? Is there a required condition?
      Always
      What is the expected behavior? Why is that the expected behavior?
      fast: [ '0', '1' ]bufferSize: 2slow: [ '0', '1' ]
      Once the two-slot buffer is full, upstream results '2' and '3' are discarded under "drop-newest".
      
Neither consumer receives them, and the buffer never exceeds highWaterMark.
      From §13.2.2 — “Share buffering and backpressure”
      With "drop-newest", the upstream pull result is discarded.
      What do you see instead?
      fast: [ '0', '1', '2', '3' ]bufferSize: 4slow: [ '0', '1', '2', '3' ]
      The buffer grows to four entries despite highWaterMark: 2, and the stalled consumer eventually receives every batch
      Additional information
      No response
      Activity
      Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
      Metadata
      Metadata
      Assignees
      Labels
      streamIssues and PRs related to Node.js streams.
      Type
      No type
      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
        stream/iter: share() does not discard upstream results with "drop-newest" #64416
        Closed
        #64417
        Closed
        stream/iter: share() does not discard upstream results with "drop-newest"#64416
        #64417
        Assignees
        trivikr
        Labels
        streamIssues and PRs related to Node.js streams.
        Description
        @trivikr
        trivikr
        opened on Jul 11, 2026
        Version
        main
        Platform
        macOS 26.5.2

        Subsystem
        stream
        What steps will reproduce the bug?
        import{share}from'node:stream/iter';asyncfunction*source(){for(leti=0;i<4;i++)yield[newTextEncoder().encode(`${i}`)];}constshared=share(source(),{highWaterMark: 2,backpressure: 'drop-newest',});constfast=shared.pull();constslow=shared.pull();constread=async(stream)=>(awaitArray.fromAsync(stream)).flat().map((chunk)=>newTextDecoder().decode(chunk));console.log('fast:',awaitread(fast));console.log('bufferSize:',shared.bufferSize);console.log('slow:',awaitread(slow));
        How often does it reproduce? Is there a required condition?
        Always
        What is the expected behavior? Why is that the expected behavior?
        fast: [ '0', '1' ]bufferSize: 2slow: [ '0', '1' ]
        Once the two-slot buffer is full, upstream results '2' and '3' are discarded under "drop-newest".
        
Neither consumer receives them, and the buffer never exceeds highWaterMark.
        From §13.2.2 — “Share buffering and backpressure”
        With "drop-newest", the upstream pull result is discarded.
        What do you see instead?
        fast: [ '0', '1', '2', '3' ]bufferSize: 4slow: [ '0', '1', '2', '3' ]
        The buffer grows to four entries despite highWaterMark: 2, and the stalled consumer eventually receives every batch
        Additional information
        No response
        Activity
        Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
        Metadata
        Metadata
        Assignees
        Labels
        streamIssues and PRs related to Node.js streams.
        Type
        No type
        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
          stream/iter: share() does not discard upstream results with "drop-newest" #64416
          Closed
          #64417
          Closed
          stream/iter: share() does not discard upstream results with "drop-newest"#64416
          #64417
          Assignees
          trivikr
          Labels
          streamIssues and PRs related to Node.js streams.
          Description
          @trivikr
          trivikr
          opened on Jul 11, 2026
          Version
          main
          Platform
          macOS 26.5.2

          Subsystem
          stream
          What steps will reproduce the bug?
          import{share}from'node:stream/iter';asyncfunction*source(){for(leti=0;i<4;i++)yield[newTextEncoder().encode(`${i}`)];}constshared=share(source(),{highWaterMark: 2,backpressure: 'drop-newest',});constfast=shared.pull();constslow=shared.pull();constread=async(stream)=>(awaitArray.fromAsync(stream)).flat().map((chunk)=>newTextDecoder().decode(chunk));console.log('fast:',awaitread(fast));console.log('bufferSize:',shared.bufferSize);console.log('slow:',awaitread(slow));
          How often does it reproduce? Is there a required condition?
          Always
          What is the expected behavior? Why is that the expected behavior?
          fast: [ '0', '1' ]bufferSize: 2slow: [ '0', '1' ]
          Once the two-slot buffer is full, upstream results '2' and '3' are discarded under "drop-newest".
          
Neither consumer receives them, and the buffer never exceeds highWaterMark.
          From §13.2.2 — “Share buffering and backpressure”
          With "drop-newest", the upstream pull result is discarded.
          What do you see instead?
          fast: [ '0', '1', '2', '3' ]bufferSize: 4slow: [ '0', '1', '2', '3' ]
          The buffer grows to four entries despite highWaterMark: 2, and the stalled consumer eventually receives every batch
          Additional information
          No response
          Activity
          Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
          Metadata
          Metadata
          Assignees
          Labels
          streamIssues and PRs related to Node.js streams.
          Type
          No type
          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
            stream/iter: share() does not discard upstream results with "drop-newest" #64416
            Closed
            #64417
            Closed
            stream/iter: share() does not discard upstream results with "drop-newest"#64416
            #64417
            Assignees
            trivikr
            Labels
            streamIssues and PRs related to Node.js streams.
            Description
            @trivikr
            trivikr
            opened on Jul 11, 2026
            Version
            main
            Platform
            macOS 26.5.2

            Subsystem
            stream
            What steps will reproduce the bug?
            import{share}from'node:stream/iter';asyncfunction*source(){for(leti=0;i<4;i++)yield[newTextEncoder().encode(`${i}`)];}constshared=share(source(),{highWaterMark: 2,backpressure: 'drop-newest',});constfast=shared.pull();constslow=shared.pull();constread=async(stream)=>(awaitArray.fromAsync(stream)).flat().map((chunk)=>newTextDecoder().decode(chunk));console.log('fast:',awaitread(fast));console.log('bufferSize:',shared.bufferSize);console.log('slow:',awaitread(slow));
            How often does it reproduce? Is there a required condition?
            Always
            What is the expected behavior? Why is that the expected behavior?
            fast: [ '0', '1' ]bufferSize: 2slow: [ '0', '1' ]
            Once the two-slot buffer is full, upstream results '2' and '3' are discarded under "drop-newest".
            
Neither consumer receives them, and the buffer never exceeds highWaterMark.
            From §13.2.2 — “Share buffering and backpressure”
            With "drop-newest", the upstream pull result is discarded.
            What do you see instead?
            fast: [ '0', '1', '2', '3' ]bufferSize: 4slow: [ '0', '1', '2', '3' ]
            The buffer grows to four entries despite highWaterMark: 2, and the stalled consumer eventually receives every batch
            Additional information
            No response
            Activity
            Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
            Metadata
            Metadata
            Assignees
            Labels
            streamIssues and PRs related to Node.js streams.
            Type
            No type
            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
              stream/iter: share() does not discard upstream results with "drop-newest" #64416
              Closed
              #64417
              Closed
              stream/iter: share() does not discard upstream results with "drop-newest"#64416
              #64417
              Assignees
              trivikr
              Labels
              streamIssues and PRs related to Node.js streams.
              Description
              @trivikr
              trivikr
              opened on Jul 11, 2026
              Version
              main
              Platform
              macOS 26.5.2

              Subsystem
              stream
              What steps will reproduce the bug?
              import{share}from'node:stream/iter';asyncfunction*source(){for(leti=0;i<4;i++)yield[newTextEncoder().encode(`${i}`)];}constshared=share(source(),{highWaterMark: 2,backpressure: 'drop-newest',});constfast=shared.pull();constslow=shared.pull();constread=async(stream)=>(awaitArray.fromAsync(stream)).flat().map((chunk)=>newTextDecoder().decode(chunk));console.log('fast:',awaitread(fast));console.log('bufferSize:',shared.bufferSize);console.log('slow:',awaitread(slow));
              How often does it reproduce? Is there a required condition?
              Always
              What is the expected behavior? Why is that the expected behavior?
              fast: [ '0', '1' ]bufferSize: 2slow: [ '0', '1' ]
              Once the two-slot buffer is full, upstream results '2' and '3' are discarded under "drop-newest".
              
Neither consumer receives them, and the buffer never exceeds highWaterMark.
              From §13.2.2 — “Share buffering and backpressure”
              With "drop-newest", the upstream pull result is discarded.
              What do you see instead?
              fast: [ '0', '1', '2', '3' ]bufferSize: 4slow: [ '0', '1', '2', '3' ]
              The buffer grows to four entries despite highWaterMark: 2, and the stalled consumer eventually receives every batch
              Additional information
              No response
              Activity
              Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
              Metadata
              Metadata
              Assignees
              Labels
              streamIssues and PRs related to Node.js streams.
              Type
              No type
              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); }
})();
})();

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                stream/iter: share() does not discard upstream results with "drop-newest" #64416
                Closed
                #64417
                Closed
                stream/iter: share() does not discard upstream results with "drop-newest"#64416
                #64417
                Assignees
                trivikr
                Labels
                streamIssues and PRs related to Node.js streams.
                Description
                @trivikr
                trivikr
                opened on Jul 11, 2026
                Version
                main
                Platform
                macOS 26.5.2

                Subsystem
                stream
                What steps will reproduce the bug?
                import{share}from'node:stream/iter';asyncfunction*source(){for(leti=0;i<4;i++)yield[newTextEncoder().encode(`${i}`)];}constshared=share(source(),{highWaterMark: 2,backpressure: 'drop-newest',});constfast=shared.pull();constslow=shared.pull();constread=async(stream)=>(awaitArray.fromAsync(stream)).flat().map((chunk)=>newTextDecoder().decode(chunk));console.log('fast:',awaitread(fast));console.log('bufferSize:',shared.bufferSize);console.log('slow:',awaitread(slow));
                How often does it reproduce? Is there a required condition?
                Always
                What is the expected behavior? Why is that the expected behavior?
                fast: [ '0', '1' ]bufferSize: 2slow: [ '0', '1' ]
                Once the two-slot buffer is full, upstream results '2' and '3' are discarded under "drop-newest".
                
Neither consumer receives them, and the buffer never exceeds highWaterMark.
                From §13.2.2 — “Share buffering and backpressure”
                With "drop-newest", the upstream pull result is discarded.
                What do you see instead?
                fast: [ '0', '1', '2', '3' ]bufferSize: 4slow: [ '0', '1', '2', '3' ]
                The buffer grows to four entries despite highWaterMark: 2, and the stalled consumer eventually receives every batch
                Additional information
                No response
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