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记一次 .NET 某招聘网后端服务 内存暴涨分析

.NET

一：背景1. 讲故事前段时间有位朋友wx找到我，说他的程序存在内存阶段性暴涨，寻求如何解决，和朋友沟通下来，他的内存平时大概是5G 左右，在某些时点附近会暴涨到 10G+, 画个图大概就是这样 。

记一次 .NET 某招聘网后端服务 内存暴涨分析

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所以接下来就是想办法给他找到那莫名奇妙的 5-6G 是个啥，上 windbg 说话 。
二：Windbg 分析1. 判断托管还是非托管从描述上看大概率是托管层面的问题，但为了文章的完整性，我们还是用 !address -summary 和 !eeheap -gc 来看一下 。
0:000> !address -summary--- Usage Summary ---------------- RgnCount ----------- Total Size -------- %ofBusy %ofTotalFree11647f5`58f12000 (7.958 TB)99.48%<unknown>6924a`6de84000 (41.717 GB)97.90%0.51%Stack11230`16340000 ( 355.250 MB)0.81%0.00%Image40630`1607d000 ( 352.488 MB)0.81%0.00%Heap710`0c9ea000 ( 201.914 MB)0.46%0.00%TEB3740`002ec000 (2.922 MB)0.01%0.00%Other130`001c6000 (1.773 MB)0.00%0.00%PEB10`00001000 (4.000 kB)0.00%0.00%--- Type Summary (for busy) ------ RgnCount ----------- Total Size -------- %ofBusy %ofTotalMEM_PRIVATE5423a`87200000 (42.111 GB)98.83%0.51%MEM_IMAGE70330`1e5d6000 ( 485.836 MB)1.11%0.01%MEM_MAppED1130`01908000 (25.031 MB)0.06%0.00%--- State Summary ---------------- RgnCount ----------- Total Size -------- %ofBusy %ofTotalMEM_FREE11647f5`58f12000 (7.958 TB)99.48%MEM_RESERVE41658`1b873000 (32.430 GB)76.11%0.40%MEM_COMMIT84042`8b86b000 (10.180 GB)23.89%0.12%0:000> !eeheap -gcNumber of GC Heaps: 32------------------------------Heap 0 (00000000004106d0)generation 0 starts at 0x0000000082eb0e58generation 1 starts at 0x0000000082d79b20generation 2 starts at 0x000000007fff1000ephemeral segment allocation context: nonesegmentbeginallocatedsize000000007fff0000000000007fff10000000000083f801280x3f8f128(66646312)Large object heap starts at 0x000000087fff1000segmentbeginallocatedsize000000087fff0000000000087fff10000000000883fe41900x3ff3190(67056016)0000000927ff00000000000927ff1000000000092bfe24300x3ff1430(67048496)0000000a81c500000000000a81c510000000000a8221c8580x5cb858(6076504)Heap Size:Size: 0xc53ef40 (206827328) bytes.------------------------------...Heap 31 (0000000019c84130)generation 0 starts at 0x0000000844fc5170generation 1 starts at 0x0000000844f851f8generation 2 starts at 0x000000083fff1000ephemeral segment allocation context: nonesegmentbeginallocatedsize000000083fff0000000000083fff10000000000845171ca00x5180ca0(85462176)Large object heap starts at 0x00000008fbff1000segmentbeginallocatedsize00000008fbff000000000008fbff100000000008fffe22900x3ff1290(67048080)000000094bff0000000000094bff1000000000094ea2ebb80x2a3dbb8(44293048)000000096bff0000000000096bff1000000000096dbdec000x1bedc00(29285376)Heap Size:Size: 0xd79d6e8 (226088680) bytes.------------------------------GC Heap Size:Size: 0x1f1986a88 (8348265096) bytes.从卦中得知，10G的内存，托管堆吃掉了 8.3G，很明显托管层问题，知道大方向后，接下来就可以到托管堆看一看，根据过往经验程序肯定是生成了大量的类对象所致，上命令 !dumpheap -stat  。
0:000> !dumpheap -statStatistics:MTCountTotalSize Class Name...000007fe9ddd5fc034128030032640 System.ServiceModel.Description.MessagePartDescription000007fe9c4865a086634941584752 System.Xml.XmlDictionaryString000007fe9defb09893780145014448 System.Xml.XmlDictionaryString000007fe9c66bd2810505245086880 System.Collections.Generic.Dictionary`2+Entry[[System.String, mscorlib],[System.Xml.XmlDictionaryString, System.Runtime.Serialization]][]000007fe9e0f4d2011329949050864 System.Collections.Generic.Dictionary`2+Entry[[System.String, mscorlib],[System.Xml.XmlDictionaryString, System.Runtime.Serialization]][]00000000003c919044573618414438Free000007fef8f6c1684284101209974642 System.Char[]000007fef8f4f1b828497581246912848 System.Object[]000007fef8f6f0585319631670620873 System.Byte[]000007fef8f6aee023684312382587716 System.String真是皂滑弄人，并没有命中过往经验，可以看出占用最大的都是些 Byte,String,Char,Object 基础类型，其实这些基础类型排查起来很难搞，要么不断的用 -min, -max 去筛选，要么就写一个脚本对它进行分组排序，蹩脚脚本如下：
"use strict";/*按 mt 对托管堆类型的size进行分组*/let platform = 64let mtlist = ["000007fef8f4f1b8"];let maxlimit = 100;function initializeScript() { return [new host.apiVersionSupport(1, 7)]; }function log(str) { host.diagnostics.debugLog(str + "n"); }function exec(str) { log("n" + str); return host.namespace.Debugger.Utility.Control.ExecuteCommand(str); }function invokeScript() { for (var mt of mtlist) { groupby_mtsize_inheap(mt); } }//对某个类型按照size 进行分组function groupby_mtsize_inheap(mt) {var size_group = {};var commandText = "!dumpheap -mt " + mt;var output = exec(commandText);for (var line of output) {if (line == "" || line.indexOf("Address") > -1) continue;if (line.indexOf("Statistics") > -1) break;var size = parseInt(line.substring(Math.ceil(platform / 2) + 1).trim());if (!size_group[size]) size_group[size] = 0;size_group[size]++;}show_top10_format(mt, size_group);}function show_top10_format(mt, size_group) {var maparr = [];//转数组for (var size in size_group) {maparr.push({ "size": size, "count": size_group[size], "totalsize": (size * size_group[size]) });}maparr.sort(function (a, b) { return b.totalsize - a.totalsize });var topTotalSize = 0;//按size输出for (var i = 0; i < Math.min(maparr.length, maxlimit); i++) {var size = maparr[i].size;var count = maparr[i].count;var totalsize = Math.round(maparr[i].totalsize / 1024 / 1024, 2);topTotalSize += totalsizelog("size=" + size + ",count=" + count + ",totalsize=" + totalsize + "M");}log("Total:" + topTotalSize + "M");//show maxif (maparr.length > 0) {var size = maparr[0].size;var totalsize = Math.round(maparr[0].totalsize / 1024 / 1024, 2) + "M";var output = exec("!dumpheap -mt " + mt + " -min 0n" + size + " -max 0n" + size + " -short").Take(maxlimit);for (var line of output) {log(line);}}}


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