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@benfavre
Created March 18, 2026 18:20
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Flamegraph: PR #91577 hotspot in canary baseline
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<?xml version="1.0" standalone="no"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
<svg version="1.1" width="1000" height="334" onload="init(evt)" viewBox="0 0 1000 334" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
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<linearGradient id="background" y1="0" y2="1" x1="0" x2="0" >
<stop stop-color="#eeeeee" offset="5%" />
<stop stop-color="#eeeeb0" offset="95%" />
</linearGradient>
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<style type="text/css">
text { font-family:Verdana; font-size:12px; fill:rgb(0,0,0); }
#search, #ignorecase { opacity:0.1; cursor:pointer; }
#search:hover, #search.show, #ignorecase:hover, #ignorecase.show { opacity:1; }
#subtitle { text-anchor:middle; font-color:rgb(160,160,160); }
#title { text-anchor:middle; font-size:17px}
#unzoom { cursor:pointer; }
#frames > *:hover { stroke:black; stroke-width:0.5; cursor:pointer; }
.hide { display:none; }
.parent { opacity:0.5; }
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<script type="text/ecmascript">
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var details, searchbtn, unzoombtn, matchedtxt, svg, searching, currentSearchTerm, ignorecase, ignorecaseBtn;
function init(evt) {
details = document.getElementById("details").firstChild;
searchbtn = document.getElementById("search");
ignorecaseBtn = document.getElementById("ignorecase");
unzoombtn = document.getElementById("unzoom");
matchedtxt = document.getElementById("matched");
svg = document.getElementsByTagName("svg")[0];
searching = 0;
currentSearchTerm = null;
// use GET parameters to restore a flamegraphs state.
var params = get_params();
if (params.x && params.y)
zoom(find_group(document.querySelector('[x="' + params.x + '"][y="' + params.y + '"]')));
if (params.s) search(params.s);
}
// event listeners
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if (target) {
if (target.nodeName == "a") {
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zoom(target);
if (!document.querySelector('.parent')) {
// we have basically done a clearzoom so clear the url
var params = get_params();
if (params.x) delete params.x;
if (params.y) delete params.y;
history.replaceState(null, null, parse_params(params));
unzoombtn.classList.add("hide");
return;
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// set parameters for zoom state
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params.y = el.attributes.y.value;
history.replaceState(null, null, parse_params(params));
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else if (e.target.id == "unzoom") clearzoom();
else if (e.target.id == "search") search_prompt();
else if (e.target.id == "ignorecase") toggle_ignorecase();
}, false)
// mouse-over for info
// show
window.addEventListener("mouseover", function(e) {
var target = find_group(e.target);
if (target) details.nodeValue = "Function: " + g_to_text(target);
}, false)
// clear
window.addEventListener("mouseout", function(e) {
var target = find_group(e.target);
if (target) details.nodeValue = ' ';
}, false)
// ctrl-F for search
// ctrl-I to toggle case-sensitive search
window.addEventListener("keydown",function (e) {
if (e.keyCode === 114 || (e.ctrlKey && e.keyCode === 70)) {
e.preventDefault();
search_prompt();
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else if (e.ctrlKey && e.keyCode === 73) {
e.preventDefault();
toggle_ignorecase();
}
}, false)
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var params = {};
var paramsarr = window.location.search.substr(1).split('&');
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var tmp = paramsarr[i].split("=");
if (!tmp[0] || !tmp[1]) continue;
params[tmp[0]] = decodeURIComponent(tmp[1]);
}
return params;
}
function parse_params(params) {
var uri = "?";
for (var key in params) {
uri += key + '=' + encodeURIComponent(params[key]) + '&';
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if (uri.slice(-1) == "&")
uri = uri.substring(0, uri.length - 1);
if (uri == '?')
uri = window.location.href.split('?')[0];
return uri;
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function find_child(node, selector) {
var children = node.querySelectorAll(selector);
if (children.length) return children[0];
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function find_group(node) {
var parent = node.parentElement;
if (!parent) return;
if (parent.id == "frames") return node;
return find_group(parent);
}
function orig_save(e, attr, val) {
if (e.attributes["_orig_" + attr] != undefined) return;
if (e.attributes[attr] == undefined) return;
if (val == undefined) val = e.attributes[attr].value;
e.setAttribute("_orig_" + attr, val);
}
function orig_load(e, attr) {
if (e.attributes["_orig_"+attr] == undefined) return;
e.attributes[attr].value = e.attributes["_orig_" + attr].value;
e.removeAttribute("_orig_"+attr);
}
function g_to_text(e) {
var text = find_child(e, "title").firstChild.nodeValue;
return (text)
}
function g_to_func(e) {
var func = g_to_text(e);
// if there's any manipulation we want to do to the function
// name before it's searched, do it here before returning.
return (func);
}
function update_text(e) {
var r = find_child(e, "rect");
var t = find_child(e, "text");
var w = parseFloat(r.attributes.width.value) -3;
var txt = find_child(e, "title").textContent.replace(/\([^(]*\)$/,"");
t.attributes.x.value = parseFloat(r.attributes.x.value) + 3;
// Smaller than this size won't fit anything
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t.textContent = "";
return;
}
t.textContent = txt;
var sl = t.getSubStringLength(0, txt.length);
// check if only whitespace or if we can fit the entire string into width w
if (/^ *$/.test(txt) || sl < w)
return;
// this isn't perfect, but gives a good starting point
// and avoids calling getSubStringLength too often
var start = Math.floor((w/sl) * txt.length);
for (var x = start; x > 0; x = x-2) {
if (t.getSubStringLength(0, x + 2) <= w) {
t.textContent = txt.substring(0, x) + "..";
return;
}
}
t.textContent = "";
}
// zoom
function zoom_reset(e) {
if (e.attributes != undefined) {
orig_load(e, "x");
orig_load(e, "width");
}
if (e.childNodes == undefined) return;
for (var i = 0, c = e.childNodes; i < c.length; i++) {
zoom_reset(c[i]);
}
}
function zoom_child(e, x, ratio) {
if (e.attributes != undefined) {
if (e.attributes.x != undefined) {
orig_save(e, "x");
e.attributes.x.value = (parseFloat(e.attributes.x.value) - x - 10) * ratio + 10;
if (e.tagName == "text")
e.attributes.x.value = find_child(e.parentNode, "rect[x]").attributes.x.value + 3;
}
if (e.attributes.width != undefined) {
orig_save(e, "width");
e.attributes.width.value = parseFloat(e.attributes.width.value) * ratio;
}
}
if (e.childNodes == undefined) return;
for (var i = 0, c = e.childNodes; i < c.length; i++) {
zoom_child(c[i], x - 10, ratio);
}
}
function zoom_parent(e) {
if (e.attributes) {
if (e.attributes.x != undefined) {
orig_save(e, "x");
e.attributes.x.value = 10;
}
if (e.attributes.width != undefined) {
orig_save(e, "width");
e.attributes.width.value = parseInt(svg.width.baseVal.value) - (10 * 2);
}
}
if (e.childNodes == undefined) return;
for (var i = 0, c = e.childNodes; i < c.length; i++) {
zoom_parent(c[i]);
}
}
function zoom(node) {
var attr = find_child(node, "rect").attributes;
var width = parseFloat(attr.width.value);
var xmin = parseFloat(attr.x.value);
var xmax = parseFloat(xmin + width);
var ymin = parseFloat(attr.y.value);
var ratio = (svg.width.baseVal.value - 2 * 10) / width;
// XXX: Workaround for JavaScript float issues (fix me)
var fudge = 0.0001;
unzoombtn.classList.remove("hide");
var el = document.getElementById("frames").children;
for (var i = 0; i < el.length; i++) {
var e = el[i];
var a = find_child(e, "rect").attributes;
var ex = parseFloat(a.x.value);
var ew = parseFloat(a.width.value);
var upstack;
// Is it an ancestor
if (0 == 0) {
upstack = parseFloat(a.y.value) > ymin;
} else {
upstack = parseFloat(a.y.value) < ymin;
}
if (upstack) {
// Direct ancestor
if (ex <= xmin && (ex+ew+fudge) >= xmax) {
e.classList.add("parent");
zoom_parent(e);
update_text(e);
}
// not in current path
else
e.classList.add("hide");
}
// Children maybe
else {
// no common path
if (ex < xmin || ex + fudge >= xmax) {
e.classList.add("hide");
}
else {
zoom_child(e, xmin, ratio);
update_text(e);
}
}
}
search();
}
function unzoom(dont_update_text) {
unzoombtn.classList.add("hide");
var el = document.getElementById("frames").children;
for(var i = 0; i < el.length; i++) {
el[i].classList.remove("parent");
el[i].classList.remove("hide");
zoom_reset(el[i]);
if(!dont_update_text) update_text(el[i]);
}
search();
}
function clearzoom() {
unzoom();
// remove zoom state
var params = get_params();
if (params.x) delete params.x;
if (params.y) delete params.y;
history.replaceState(null, null, parse_params(params));
}
// search
function toggle_ignorecase() {
ignorecase = !ignorecase;
if (ignorecase) {
ignorecaseBtn.classList.add("show");
} else {
ignorecaseBtn.classList.remove("show");
}
reset_search();
search();
}
function reset_search() {
var el = document.querySelectorAll("#frames rect");
for (var i = 0; i < el.length; i++) {
orig_load(el[i], "fill")
}
var params = get_params();
delete params.s;
history.replaceState(null, null, parse_params(params));
}
function search_prompt() {
if (!searching) {
var term = prompt("Enter a search term (regexp " +
"allowed, eg: ^ext4_)"
+ (ignorecase ? ", ignoring case" : "")
+ "\nPress Ctrl-i to toggle case sensitivity", "");
if (term != null) search(term);
} else {
reset_search();
searching = 0;
currentSearchTerm = null;
searchbtn.classList.remove("show");
searchbtn.firstChild.nodeValue = "Search"
matchedtxt.classList.add("hide");
matchedtxt.firstChild.nodeValue = ""
}
}
function search(term) {
if (term) currentSearchTerm = term;
if (currentSearchTerm === null) return;
var re = new RegExp(currentSearchTerm, ignorecase ? 'i' : '');
var el = document.getElementById("frames").children;
var matches = new Object();
var maxwidth = 0;
for (var i = 0; i < el.length; i++) {
var e = el[i];
var func = g_to_func(e);
var rect = find_child(e, "rect");
if (func == null || rect == null)
continue;
// Save max width. Only works as we have a root frame
var w = parseFloat(rect.attributes.width.value);
if (w > maxwidth)
maxwidth = w;
if (func.match(re)) {
// highlight
var x = parseFloat(rect.attributes.x.value);
orig_save(rect, "fill");
rect.attributes.fill.value = "rgb(230,0,230)";
// remember matches
if (matches[x] == undefined) {
matches[x] = w;
} else {
if (w > matches[x]) {
// overwrite with parent
matches[x] = w;
}
}
searching = 1;
}
}
if (!searching)
return;
var params = get_params();
params.s = currentSearchTerm;
history.replaceState(null, null, parse_params(params));
searchbtn.classList.add("show");
searchbtn.firstChild.nodeValue = "Reset Search";
// calculate percent matched, excluding vertical overlap
var count = 0;
var lastx = -1;
var lastw = 0;
var keys = Array();
for (k in matches) {
if (matches.hasOwnProperty(k))
keys.push(k);
}
// sort the matched frames by their x location
// ascending, then width descending
keys.sort(function(a, b){
return a - b;
});
// Step through frames saving only the biggest bottom-up frames
// thanks to the sort order. This relies on the tree property
// where children are always smaller than their parents.
var fudge = 0.0001; // JavaScript floating point
for (var k in keys) {
var x = parseFloat(keys[k]);
var w = matches[keys[k]];
if (x >= lastx + lastw - fudge) {
count += w;
lastx = x;
lastw = w;
}
}
// display matched percent
matchedtxt.classList.remove("hide");
var pct = 100 * count / maxwidth;
if (pct != 100) pct = pct.toFixed(1)
matchedtxt.firstChild.nodeValue = "Matched: " + pct + "%";
}
]]>
</script>
<rect x="0.0" y="0" width="1000.0" height="334.0" fill="url(#background)" />
<text id="title" x="500.00" y="24" >PR #91577: structuredClone in metadata resolution (ELIMINATED)</text>
<text id="subtitle" x="500.00" y="48" >CPU time in canary baseline attributed to this hotspot</text>
<text id="details" x="10.00" y="317" > </text>
<text id="unzoom" x="10.00" y="24" class="hide">Reset Zoom</text>
<text id="search" x="890.00" y="24" >Search</text>
<text id="ignorecase" x="974.00" y="24" >ic</text>
<text id="matched" x="890.00" y="317" > </text>
<g id="frames">
<g >
<title>render (78 μs, 31.33%)</title><rect x="10.0" y="125" width="307.0" height="15.0" fill="rgb(229,111,26)" rx="2" ry="2" />
<text x="13.00" y="135.5" >render</text>
</g>
<g >
<title>handleRewrites (67 μs, 26.91%)</title><rect x="726.3" y="205" width="263.7" height="15.0" fill="rgb(248,198,47)" rx="2" ry="2" />
<text x="729.31" y="215.5" >handleRewrites</text>
</g>
<g >
<title>processTicksAndRejections (249 μs, 100.00%)</title><rect x="10.0" y="253" width="980.0" height="15.0" fill="rgb(230,118,28)" rx="2" ry="2" />
<text x="13.00" y="263.5" >processTicksAndRejections</text>
</g>
<g >
<title>prepare (171 μs, 68.67%)</title><rect x="317.0" y="221" width="673.0" height="15.0" fill="rgb(212,32,7)" rx="2" ry="2" />
<text x="319.99" y="231.5" >prepare</text>
</g>
<g >
<title>structuredClone (78 μs, 31.33%)</title><rect x="10.0" y="77" width="307.0" height="15.0" fill="rgb(238,156,37)" rx="2" ry="2" />
<text x="13.00" y="87.5" >structuredClone</text>
</g>
<g >
<title>handleResponse (78 μs, 31.33%)</title><rect x="10.0" y="221" width="307.0" height="15.0" fill="rgb(236,146,35)" rx="2" ry="2" />
<text x="13.00" y="231.5" >handleResponse</text>
</g>
<g >
<title>m (78 μs, 31.33%)</title><rect x="10.0" y="157" width="307.0" height="15.0" fill="rgb(209,20,4)" rx="2" ry="2" />
<text x="13.00" y="167.5" >m</text>
</g>
<g >
<title>d.prefixRouteKeys (104 μs, 41.77%)</title><rect x="317.0" y="189" width="409.3" height="15.0" fill="rgb(229,114,27)" rx="2" ry="2" />
<text x="319.99" y="199.5" >d.prefixRouteKeys</text>
</g>
<g >
<title>structuredClone (104 μs, 41.77%)</title><rect x="317.0" y="173" width="409.3" height="15.0" fill="rgb(238,156,37)" rx="2" ry="2" />
<text x="319.99" y="183.5" >structuredClone</text>
</g>
<g >
<title>responseGenerator (78 μs, 31.33%)</title><rect x="10.0" y="189" width="307.0" height="15.0" fill="rgb(245,185,44)" rx="2" ry="2" />
<text x="13.00" y="199.5" >responseGenerator</text>
</g>
<g >
<title>i (78 μs, 31.33%)</title><rect x="10.0" y="141" width="307.0" height="15.0" fill="rgb(235,139,33)" rx="2" ry="2" />
<text x="13.00" y="151.5" >i</text>
</g>
<g >
<title>structuredClone (8 μs, 3.21%)</title><rect x="958.5" y="173" width="31.5" height="15.0" fill="rgb(238,156,37)" rx="2" ry="2" />
<text x="961.51" y="183.5" >st..</text>
</g>
<g >
<title>runMicrotasks (249 μs, 100.00%)</title><rect x="10.0" y="237" width="980.0" height="15.0" fill="rgb(239,156,37)" rx="2" ry="2" />
<text x="13.00" y="247.5" >runMicrotasks</text>
</g>
<g >
<title>get (78 μs, 31.33%)</title><rect x="10.0" y="205" width="307.0" height="15.0" fill="rgb(246,190,45)" rx="2" ry="2" />
<text x="13.00" y="215.5" >get</text>
</g>
<g >
<title>structuredClone (26 μs, 10.44%)</title><rect x="214.7" y="61" width="102.3" height="15.0" fill="rgb(238,156,37)" rx="2" ry="2" />
<text x="217.66" y="71.5" >structuredCl..</text>
</g>
<g >
<title>(root) (249 μs, 100.00%)</title><rect x="10.0" y="269" width="980.0" height="15.0" fill="rgb(220,70,16)" rx="2" ry="2" />
<text x="13.00" y="279.5" >(root)</text>
</g>
<g >
<title>structuredClone (67 μs, 26.91%)</title><rect x="726.3" y="189" width="263.7" height="15.0" fill="rgb(238,156,37)" rx="2" ry="2" />
<text x="729.31" y="199.5" >structuredClone</text>
</g>
<g >
<title>structuredClone (21 μs, 8.43%)</title><rect x="643.7" y="157" width="82.6" height="15.0" fill="rgb(238,156,37)" rx="2" ry="2" />
<text x="646.65" y="167.5" >structure..</text>
</g>
<g >
<title>A.page (104 μs, 41.77%)</title><rect x="317.0" y="205" width="409.3" height="15.0" fill="rgb(228,108,25)" rx="2" ry="2" />
<text x="319.99" y="215.5" >A.page</text>
</g>
<g >
<title>lC (78 μs, 31.33%)</title><rect x="10.0" y="109" width="307.0" height="15.0" fill="rgb(233,129,30)" rx="2" ry="2" />
<text x="13.00" y="119.5" >lC</text>
</g>
<g >
<title>nx (78 μs, 31.33%)</title><rect x="10.0" y="93" width="307.0" height="15.0" fill="rgb(227,104,25)" rx="2" ry="2" />
<text x="13.00" y="103.5" >nx</text>
</g>
<g >
<title>n (78 μs, 31.33%)</title><rect x="10.0" y="173" width="307.0" height="15.0" fill="rgb(252,220,52)" rx="2" ry="2" />
<text x="13.00" y="183.5" >n</text>
</g>
<g >
<title>all (249 μs, 100%)</title><rect x="10.0" y="285" width="980.0" height="15.0" fill="rgb(213,39,9)" rx="2" ry="2" />
<text x="13.00" y="295.5" ></text>
</g>
</g>
</svg>
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