Repeated commits for mark array #75207

Closed
Closed
Repeated commits for mark array#75207
Labels
area-GC-coreclr
Milestone
8.0.0

Description

@cshung
cshung
opened on Sep 7, 2022

Suppose we have a region that has the associated mark array committed. It is returned to the free region list through return_free_region and then got back to the heap through get_free_region. The code in init_heap_segment called by get_free_region will reset the heap_segment_flags_ma_committed flag and we will commit the mark array again when we need it.

In case we are running on a supported platform where duplicated virtual_commit to the same address range is non-fatal, it is fine.

On certain platforms, repeated virtual_commit to the same address range is fatal. Even in the case that it isn't fatal, in the presence of a hard limit, this will repeatedly consume the hard limit, so we will eventually "run out of memory" just because the number is leaked and we think the system is running out of committed bytes when it actually isn't.

To reproduce the issue, check out my private branch here.

Note: This branch requires the use of heap_hard_limit, it will assert and crash otherwise.

The branch features a heap segment analyzer that can be used to detect the case when we have overlapped virtual commits, which can be used to detect the bug as follow:

We can run GCPerfSim with these parameters (with a release build of the Core_Root built on the branch):

GCPerfSim.dll -tc 6 -tagb 100.0 -tlgb 0.01 -lohar 0 -pohar 0 -sohsi 10 -lohsi 0 -pohsi 0 -sohsr 100-4000 -lohsr 102400-204800 -pohsr 100-4000 -sohpi 10 -lohpi 0 -sohfi 0 -lohfi 0 -pohfi 0 -allocType reference -testKind time

and these environment variables:

COMPlus_GCHeapCount=6
COMPlus_GCHeapHardLimit=1C200000
COMPlus_GCServer=1

This will generate a file named andrew.txt, running analyze.py with that file will lead to the tool detecting the overlap.

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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
      Repeated commits for mark array #75207
      Closed
      Closed
      Repeated commits for mark array#75207
      Labels
      area-GC-coreclr
      Milestone
      8.0.0
      Description
      @cshung
      cshung
      opened on Sep 7, 2022
      Suppose we have a region that has the associated mark array committed. It is returned to the free region list through return_free_region and then got back to the heap through get_free_region. The code in init_heap_segment called by get_free_region will reset the heap_segment_flags_ma_committed flag and we will commit the mark array again when we need it.
      In case we are running on a supported platform where duplicated virtual_commit to the same address range is non-fatal, it is fine.
      On certain platforms, repeated virtual_commit to the same address range is fatal. Even in the case that it isn't fatal, in the presence of a hard limit, this will repeatedly consume the hard limit, so we will eventually "run out of memory" just because the number is leaked and we think the system is running out of committed bytes when it actually isn't.
      To reproduce the issue, check out my private branch here.
      Note: This branch requires the use of heap_hard_limit, it will assert and crash otherwise.
      The branch features a heap segment analyzer that can be used to detect the case when we have overlapped virtual commits, which can be used to detect the bug as follow:
      We can run GCPerfSim with these parameters (with a release build of the Core_Root built on the branch):
      GCPerfSim.dll -tc 6 -tagb 100.0 -tlgb 0.01 -lohar 0 -pohar 0 -sohsi 10 -lohsi 0 -pohsi 0 -sohsr 100-4000 -lohsr 102400-204800 -pohsr 100-4000 -sohpi 10 -lohpi 0 -sohfi 0 -lohfi 0 -pohfi 0 -allocType reference -testKind time

      and these environment variables:
      COMPlus_GCHeapCount=6
COMPlus_GCHeapHardLimit=1C200000
COMPlus_GCServer=1

      This will generate a file named andrew.txt, running analyze.py with that file will lead to the tool detecting the overlap.
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        area-GC-coreclr
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, '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
          Repeated commits for mark array #75207
          Closed
          Closed
          Repeated commits for mark array#75207
          Labels
          area-GC-coreclr
          Milestone
          8.0.0
          Description
          @cshung
          cshung
          opened on Sep 7, 2022
          Suppose we have a region that has the associated mark array committed. It is returned to the free region list through return_free_region and then got back to the heap through get_free_region. The code in init_heap_segment called by get_free_region will reset the heap_segment_flags_ma_committed flag and we will commit the mark array again when we need it.
          In case we are running on a supported platform where duplicated virtual_commit to the same address range is non-fatal, it is fine.
          On certain platforms, repeated virtual_commit to the same address range is fatal. Even in the case that it isn't fatal, in the presence of a hard limit, this will repeatedly consume the hard limit, so we will eventually "run out of memory" just because the number is leaked and we think the system is running out of committed bytes when it actually isn't.
          To reproduce the issue, check out my private branch here.
          Note: This branch requires the use of heap_hard_limit, it will assert and crash otherwise.
          The branch features a heap segment analyzer that can be used to detect the case when we have overlapped virtual commits, which can be used to detect the bug as follow:
          We can run GCPerfSim with these parameters (with a release build of the Core_Root built on the branch):
          GCPerfSim.dll -tc 6 -tagb 100.0 -tlgb 0.01 -lohar 0 -pohar 0 -sohsi 10 -lohsi 0 -pohsi 0 -sohsr 100-4000 -lohsr 102400-204800 -pohsr 100-4000 -sohpi 10 -lohpi 0 -sohfi 0 -lohfi 0 -pohfi 0 -allocType reference -testKind time

          and these environment variables:
          COMPlus_GCHeapCount=6
COMPlus_GCHeapHardLimit=1C200000
COMPlus_GCServer=1

          This will generate a file named andrew.txt, running analyze.py with that file will lead to the tool detecting the overlap.
          Metadata
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          No one assigned
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            area-GC-coreclr
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              None yet
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              No branches or pull requests
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, '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
              Repeated commits for mark array #75207
              Closed
              Closed
              Repeated commits for mark array#75207
              Labels
              area-GC-coreclr
              Milestone
              8.0.0
              Description
              @cshung
              cshung
              opened on Sep 7, 2022
              Suppose we have a region that has the associated mark array committed. It is returned to the free region list through return_free_region and then got back to the heap through get_free_region. The code in init_heap_segment called by get_free_region will reset the heap_segment_flags_ma_committed flag and we will commit the mark array again when we need it.
              In case we are running on a supported platform where duplicated virtual_commit to the same address range is non-fatal, it is fine.
              On certain platforms, repeated virtual_commit to the same address range is fatal. Even in the case that it isn't fatal, in the presence of a hard limit, this will repeatedly consume the hard limit, so we will eventually "run out of memory" just because the number is leaked and we think the system is running out of committed bytes when it actually isn't.
              To reproduce the issue, check out my private branch here.
              Note: This branch requires the use of heap_hard_limit, it will assert and crash otherwise.
              The branch features a heap segment analyzer that can be used to detect the case when we have overlapped virtual commits, which can be used to detect the bug as follow:
              We can run GCPerfSim with these parameters (with a release build of the Core_Root built on the branch):
              GCPerfSim.dll -tc 6 -tagb 100.0 -tlgb 0.01 -lohar 0 -pohar 0 -sohsi 10 -lohsi 0 -pohsi 0 -sohsr 100-4000 -lohsr 102400-204800 -pohsr 100-4000 -sohpi 10 -lohpi 0 -sohfi 0 -lohfi 0 -pohfi 0 -allocType reference -testKind time

              and these environment variables:
              COMPlus_GCHeapCount=6
COMPlus_GCHeapHardLimit=1C200000
COMPlus_GCServer=1

              This will generate a file named andrew.txt, running analyze.py with that file will lead to the tool detecting the overlap.
              Metadata
              Metadata
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              No one assigned
                Labels
                area-GC-coreclr
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                No type
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                  None yet
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                  No branches or pull requests
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, '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
                  Repeated commits for mark array #75207
                  Closed
                  Closed
                  Repeated commits for mark array#75207
                  Labels
                  area-GC-coreclr
                  Milestone
                  8.0.0
                  Description
                  @cshung
                  cshung
                  opened on Sep 7, 2022
                  Suppose we have a region that has the associated mark array committed. It is returned to the free region list through return_free_region and then got back to the heap through get_free_region. The code in init_heap_segment called by get_free_region will reset the heap_segment_flags_ma_committed flag and we will commit the mark array again when we need it.
                  In case we are running on a supported platform where duplicated virtual_commit to the same address range is non-fatal, it is fine.
                  On certain platforms, repeated virtual_commit to the same address range is fatal. Even in the case that it isn't fatal, in the presence of a hard limit, this will repeatedly consume the hard limit, so we will eventually "run out of memory" just because the number is leaked and we think the system is running out of committed bytes when it actually isn't.
                  To reproduce the issue, check out my private branch here.
                  Note: This branch requires the use of heap_hard_limit, it will assert and crash otherwise.
                  The branch features a heap segment analyzer that can be used to detect the case when we have overlapped virtual commits, which can be used to detect the bug as follow:
                  We can run GCPerfSim with these parameters (with a release build of the Core_Root built on the branch):
                  GCPerfSim.dll -tc 6 -tagb 100.0 -tlgb 0.01 -lohar 0 -pohar 0 -sohsi 10 -lohsi 0 -pohsi 0 -sohsr 100-4000 -lohsr 102400-204800 -pohsr 100-4000 -sohpi 10 -lohpi 0 -sohfi 0 -lohfi 0 -pohfi 0 -allocType reference -testKind time

                  and these environment variables:
                  COMPlus_GCHeapCount=6
COMPlus_GCHeapHardLimit=1C200000
COMPlus_GCServer=1

                  This will generate a file named andrew.txt, running analyze.py with that file will lead to the tool detecting the overlap.
                  Metadata
                  Metadata
                  Assignees
                  No one assigned
                    Labels
                    area-GC-coreclr
                    Type
                    No type
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                    No projects
                      Milestone
                      Relationships
                      None yet
                      Development
                      No branches or pull requests
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, '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
                      Repeated commits for mark array #75207
                      Closed
                      Closed
                      Repeated commits for mark array#75207
                      Labels
                      area-GC-coreclr
                      Milestone
                      8.0.0
                      Description
                      @cshung
                      cshung
                      opened on Sep 7, 2022
                      Suppose we have a region that has the associated mark array committed. It is returned to the free region list through return_free_region and then got back to the heap through get_free_region. The code in init_heap_segment called by get_free_region will reset the heap_segment_flags_ma_committed flag and we will commit the mark array again when we need it.
                      In case we are running on a supported platform where duplicated virtual_commit to the same address range is non-fatal, it is fine.
                      On certain platforms, repeated virtual_commit to the same address range is fatal. Even in the case that it isn't fatal, in the presence of a hard limit, this will repeatedly consume the hard limit, so we will eventually "run out of memory" just because the number is leaked and we think the system is running out of committed bytes when it actually isn't.
                      To reproduce the issue, check out my private branch here.
                      Note: This branch requires the use of heap_hard_limit, it will assert and crash otherwise.
                      The branch features a heap segment analyzer that can be used to detect the case when we have overlapped virtual commits, which can be used to detect the bug as follow:
                      We can run GCPerfSim with these parameters (with a release build of the Core_Root built on the branch):
                      GCPerfSim.dll -tc 6 -tagb 100.0 -tlgb 0.01 -lohar 0 -pohar 0 -sohsi 10 -lohsi 0 -pohsi 0 -sohsr 100-4000 -lohsr 102400-204800 -pohsr 100-4000 -sohpi 10 -lohpi 0 -sohfi 0 -lohfi 0 -pohfi 0 -allocType reference -testKind time

                      and these environment variables:
                      COMPlus_GCHeapCount=6
COMPlus_GCHeapHardLimit=1C200000
COMPlus_GCServer=1

                      This will generate a file named andrew.txt, running analyze.py with that file will lead to the tool detecting the overlap.
                      Metadata
                      Metadata
                      Assignees
                      No one assigned
                        Labels
                        area-GC-coreclr
                        Type
                        No type
                        Projects
                        No projects
                          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
                          Repeated commits for mark array #75207
                          Closed
                          Closed
                          Repeated commits for mark array#75207
                          Labels
                          area-GC-coreclr
                          Milestone
                          8.0.0
                          Description
                          @cshung
                          cshung
                          opened on Sep 7, 2022
                          Suppose we have a region that has the associated mark array committed. It is returned to the free region list through return_free_region and then got back to the heap through get_free_region. The code in init_heap_segment called by get_free_region will reset the heap_segment_flags_ma_committed flag and we will commit the mark array again when we need it.
                          In case we are running on a supported platform where duplicated virtual_commit to the same address range is non-fatal, it is fine.
                          On certain platforms, repeated virtual_commit to the same address range is fatal. Even in the case that it isn't fatal, in the presence of a hard limit, this will repeatedly consume the hard limit, so we will eventually "run out of memory" just because the number is leaked and we think the system is running out of committed bytes when it actually isn't.
                          To reproduce the issue, check out my private branch here.
                          Note: This branch requires the use of heap_hard_limit, it will assert and crash otherwise.
                          The branch features a heap segment analyzer that can be used to detect the case when we have overlapped virtual commits, which can be used to detect the bug as follow:
                          We can run GCPerfSim with these parameters (with a release build of the Core_Root built on the branch):
                          GCPerfSim.dll -tc 6 -tagb 100.0 -tlgb 0.01 -lohar 0 -pohar 0 -sohsi 10 -lohsi 0 -pohsi 0 -sohsr 100-4000 -lohsr 102400-204800 -pohsr 100-4000 -sohpi 10 -lohpi 0 -sohfi 0 -lohfi 0 -pohfi 0 -allocType reference -testKind time

                          and these environment variables:
                          COMPlus_GCHeapCount=6
COMPlus_GCHeapHardLimit=1C200000
COMPlus_GCServer=1

                          This will generate a file named andrew.txt, running analyze.py with that file will lead to the tool detecting the overlap.
                          Metadata
                          Metadata
                          Assignees
                          No one assigned
                            Labels
                            area-GC-coreclr
                            Type
                            No type
                            Projects
                            No projects
                              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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                              Repeated commits for mark array #75207
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                              Closed
                              Repeated commits for mark array#75207
                              Labels
                              area-GC-coreclr
                              Milestone
                              8.0.0
                              Description
                              @cshung
                              cshung
                              opened on Sep 7, 2022
                              Suppose we have a region that has the associated mark array committed. It is returned to the free region list through return_free_region and then got back to the heap through get_free_region. The code in init_heap_segment called by get_free_region will reset the heap_segment_flags_ma_committed flag and we will commit the mark array again when we need it.
                              In case we are running on a supported platform where duplicated virtual_commit to the same address range is non-fatal, it is fine.
                              On certain platforms, repeated virtual_commit to the same address range is fatal. Even in the case that it isn't fatal, in the presence of a hard limit, this will repeatedly consume the hard limit, so we will eventually "run out of memory" just because the number is leaked and we think the system is running out of committed bytes when it actually isn't.
                              To reproduce the issue, check out my private branch here.
                              Note: This branch requires the use of heap_hard_limit, it will assert and crash otherwise.
                              The branch features a heap segment analyzer that can be used to detect the case when we have overlapped virtual commits, which can be used to detect the bug as follow:
                              We can run GCPerfSim with these parameters (with a release build of the Core_Root built on the branch):
                              GCPerfSim.dll -tc 6 -tagb 100.0 -tlgb 0.01 -lohar 0 -pohar 0 -sohsi 10 -lohsi 0 -pohsi 0 -sohsr 100-4000 -lohsr 102400-204800 -pohsr 100-4000 -sohpi 10 -lohpi 0 -sohfi 0 -lohfi 0 -pohfi 0 -allocType reference -testKind time

                              and these environment variables:
                              COMPlus_GCHeapCount=6
COMPlus_GCHeapHardLimit=1C200000
COMPlus_GCServer=1

                              This will generate a file named andrew.txt, running analyze.py with that file will lead to the tool detecting the overlap.
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