JVM_FindSignal 函数不断分配本机内存
我在 linux 机器上的 tomcat8 中部署的 java web 应用程序一直在泄漏本机内存，我尝试通过使用 jemalloc 分析来检测泄漏源，如下所述:
我也用过 Java Native Memory Tracking 工具查明泄漏 https://docs.oracle.com/javase/8/docs/technotes/guides/vm/nmt-8.htmlNMT 在内部"部分报告内存泄漏.调用图表明调用 JVM_FindSignal 是因为start_thread，然而，NMT diff 工具报告应用程序线程的数量几乎是恒定的，保持在 ~300.
JVM 选项:
-Xms24920m -Xmx24920m -XX:MaxMetaspaceSize=512m -XX:+AlwaysPreTouch-XX:+UseG1GC -XX:G1HeapWastePercent=10-XX:+使用TLAB-XX:+ScavengeBeforeFullGC -verbose:gc-XX:+PrintGC详情-XX:+PrintGCDateStamps -XX:+PrintTenuringDistribution-XX:+PrintGCApplicationConcurrentTime-XX:+PrintGCApplicationStoppedTime-Djava.rmi.server.hostname=XXXXX-Dcom.sun.management.jmxremote.port=XXXXX-Dcom.sun.management.jmxremote.ssl=false那么，JVM_FindSignal 已经分配了 789 兆字节的本机内存，但没有释放，有没有人知道 JVM_FindSignal 做了什么以及为什么它会不断分配内存?
解决方案JVM_FindSignal 根本不分配内存.而且这个函数通常不会在应用程序运行时经常调用.
您的 JDK 安装似乎不包含调试符号，因此 jemalloc 分析器无法找到正确的函数名称，而只能从 libjvm.so 中获取最近的公共符号.JVM_FindSignal 只是这些随机符号之一.配置文件中的其他条目看起来也有问题.例如.占 87.8% 的 AsyncGetCallTrace 也没有分配任何内容.
使用 JDK 调试符号安装单独的包可能会有所帮助.
在 Debian/Ubuntu 上:
apt install openjdk-8-dbg在 RHEL/CentOS 上:
debuginfo-install java-1.8.0-openjdkMy java web application deployed in tomcat8 on a linux machine has been leaking native memory, I've tried to detect the source of the leak by using jemalloc profiling as described here: https://github.com/jeffgriffith/native-jvm-leaks Output of the profiling tool with a heap dump on a server running for > 24 hours:
Total: 794708494 B
789734456 99.4% 99.4% 789987533 99.4% JVM_FindSignal
3421211 0.4% 99.8% 3421211 0.4% Java_java_util_zip_ZipFile_getZipMessage
1036965 0.1% 99.9% 1036965 0.1% inflateBackEnd
262784 0.0% 100.0% 262784 0.0% __GI__dl_allocate_tls
253077 0.0% 100.0% 598675182 75.3% SUNWprivate_1.1
0 0.0% 100.0% 938397 0.1% 0x00007fb133688ef8
0 0.0% 100.0% 131136 0.0% 0x00007fb133696c2e
0 0.0% 100.0% 6146839 0.8% 0x00007fb13369b553
0 0.0% 100.0% 135210 0.0% 0x00007fb1336a63f5
0 0.0% 100.0% 131136 0.0% 0x00007fb1336a6403
0 0.0% 100.0% 266290 0.0% 0x00007fb1336a7819
0 0.0% 100.0% 296275 0.0% 0x00007fb1336a7827
0 0.0% 100.0% 139434 0.0% 0x00007fb1336a845a
0 0.0% 100.0% 1221269 0.2% 0x00007fb1336a87e9
0 0.0% 100.0% 663829 0.1% 0x00007fb1336a87f7
0 0.0% 100.0% 148137 0.0% 0x00007fb1336a89f7
0 0.0% 100.0% 143743 0.0% 0x00007fb1336a9068
0 0.0% 100.0% 270421 0.0% 0x00007fb1336ab23d
0 0.0% 100.0% 135210 0.0% 0x00007fb1336ab24b
0 0.0% 100.0% 135210 0.0% 0x00007fb1336ab38b
0 0.0% 100.0% 132613 0.0% 0x00007fb1336cb294
0 0.0% 100.0% 131232 0.0% 0x00007fb1336f04da
0 0.0% 100.0% 136258 0.0% 0x00007fb133925efe
0 0.0% 100.0% 135210 0.0% 0x00007fb133927cc6
0 0.0% 100.0% 2012412 0.3% 0x00007fb133929d07
0 0.0% 100.0% 159413372 20.1% 0x00007fb1339be9a5
0 0.0% 100.0% 279249 0.0% 0x00007fb1339e897b
0 0.0% 100.0% 148137 0.0% 0x00007fb133a94545
0 0.0% 100.0% 131232 0.0% 0x00007fb133a980d4
0 0.0% 100.0% 266346 0.0% 0x00007fb133ab523b
0 0.0% 100.0% 444413 0.1% 0x00007fb133ac8727
0 0.0% 100.0% 4622703 0.6% 0x00007fb133b4c74a
0 0.0% 100.0% 270666 0.0% 0x00007fb133b91ee7
0 0.0% 100.0% 28347870 3.6% 0x00007fb133c61c4a
0 0.0% 100.0% 135210 0.0% 0x00007fb133c94425
0 0.0% 100.0% 3064228 0.4% 0x00007fb133d7c611
0 0.0% 100.0% 131080 0.0% 0x00007fb133dfc067
0 0.0% 100.0% 270421 0.0% 0x00007fb133dfc9f3
0 0.0% 100.0% 136258 0.0% 0x00007fb1340590c9
0 0.0% 100.0% 136258 0.0% 0x00007fb1340f60fc
0 0.0% 100.0% 676053 0.1% 0x00007fb13447aba7
0 0.0% 100.0% 968594 0.1% 0x00007fb13467ff67
0 0.0% 100.0% 136258 0.0% 0x00007fb134b8eba6
0 0.0% 100.0% 431231 0.1% 0x00007fb134c861a7
0 0.0% 100.0% 136258 0.0% 0x00007fb135122400
0 0.0% 100.0% 136258 0.0% 0x00007fb1352166b4
0 0.0% 100.0% 136258 0.0% 0x00007fb135807a38
0 0.0% 100.0% 136258 0.0% 0x00007fb135807ed1
0 0.0% 100.0% 136258 0.0% 0x00007fb135822eaf
0 0.0% 100.0% 297823 0.0% 0x00007fb135f85154
0 0.0% 100.0% 136258 0.0% 0x00007fb1368a7c42
0 0.0% 100.0% 1313955 0.2% 0x00007fb136e464e5
0 0.0% 100.0% 922058 0.1% 0x00007fb137245e69
0 0.0% 100.0% 408775 0.1% 0x00007fb13734a4aa
0 0.0% 100.0% 1226327 0.2% 0x00007fb13734a4d3
0 0.0% 100.0% 272517 0.0% 0x00007fb137e0760f
0 0.0% 100.0% 681293 0.1% 0x00007fb137e07624
0 0.0% 100.0% 272517 0.0% 0x00007fb137ea88f5
0 0.0% 100.0% 136258 0.0% 0x00007fb137ea8aa4
0 0.0% 100.0% 136258 0.0% 0x00007fb13876c9e9
0 0.0% 100.0% 136258 0.0% 0x00007fb138c0e8f0
0 0.0% 100.0% 272517 0.0% 0x00007fb138dca6f7
0 0.0% 100.0% 272517 0.0% 0x00007fb138dca70c
0 0.0% 100.0% 272517 0.0% 0x00007fb138dcb5ca
0 0.0% 100.0% 136258 0.0% 0x00007fb138f0dba8
0 0.0% 100.0% 136258 0.0% 0x00007fb138fe8f2e
0 0.0% 100.0% 136258 0.0% 0x00007fb13948cd05
0 0.0% 100.0% 136258 0.0% 0x00007fb139ee2f9c
0 0.0% 100.0% 408775 0.1% 0x00007fb13a03f0be
0 0.0% 100.0% 545034 0.1% 0x00007fb13a04e468
0 0.0% 100.0% 272517 0.0% 0x00007fb13a04e64e
0 0.0% 100.0% 136258 0.0% 0x00007fb13a920fca
0 0.0% 100.0% 136258 0.0% 0x00007fb13a92130b
0 0.0% 100.0% 136258 0.0% 0x00007fb13af0b151
0 0.0% 100.0% 136258 0.0% 0x00007fb13b7609a2
0 0.0% 100.0% 136258 0.0% 0x00007fb13b770cb0
0 0.0% 100.0% 408775 0.1% 0x00007fb13bd55409
0 0.0% 100.0% 136258 0.0% 0x00007fb13c062aea
0 0.0% 100.0% 136258 0.0% 0x00007fb13c06419a
0 0.0% 100.0% 136258 0.0% 0x00007fb13d264f22
0 0.0% 100.0% 136258 0.0% 0x00007fb13d264f37
0 0.0% 100.0% 136258 0.0% 0x00007fb13d265fc4
0 0.0% 100.0% 408775 0.1% 0x00007fb13d3fb048
0 0.0% 100.0% 698085685 87.8% AsyncGetCallTrace
0 0.0% 100.0% 162799014 20.5% JNI_CreateJavaVM
0 0.0% 100.0% 35102689 4.4% JNI_GetCreatedJavaVMs
0 0.0% 100.0% 131296 0.0% JNU_NewObjectByName
0 0.0% 100.0% 4766447 0.6% JVM_DefineClass
0 0.0% 100.0% 29155153 3.7% JVM_DefineClassWithSource
0 0.0% 100.0% 1204712 0.2% JVM_DoPrivileged
0 0.0% 100.0% 444413 0.1% JVM_FillInStackTrace
0 0.0% 100.0% 266346 0.0% JVM_FindClassFromBootLoader
0 0.0% 100.0% 270421 0.0% JVM_FindClassFromCaller
0 0.0% 100.0% 279249 0.0% JVM_FindLoadedClass
0 0.0% 100.0% 131080 0.0% JVM_GetClassDeclaredConstructors
0 0.0% 100.0% 824436 0.1% JVM_GetClassDeclaredFields
0 0.0% 100.0% 942399 0.1% JVM_GetClassDeclaredMethods
0 0.0% 100.0% 135210 0.0% JVM_GetClassName
0 0.0% 100.0% 159413372 20.1% JVM_InternString
0 0.0% 100.0% 253077 0.0% JVM_LoadLibrary
0 0.0% 100.0% 431231 0.1% JVM_MonitorWait
0 0.0% 100.0% 409855 0.1% JVM_RawMonitorExit
0 0.0% 100.0% 1707451 0.2% JVM_StartThread
0 0.0% 100.0% 714622614 89.9% JVM_handle_linux_signal
0 0.0% 100.0% 253077 0.0% Java_java_lang_ClassLoader_00024NativeLibrary_load
0 0.0% 100.0% 29155153 3.7% Java_java_lang_ClassLoader_defineClass1
0 0.0% 100.0% 266346 0.0% Java_java_lang_ClassLoader_findBootstrapClass
0 0.0% 100.0% 270421 0.0% Java_java_lang_Class_forName0
0 0.0% 100.0% 444413 0.1% Java_java_lang_Throwable_fillInStackTrace
0 0.0% 100.0% 131136 0.0% Java_java_lang_reflect_Proxy_defineClass0
0 0.0% 100.0% 1036965 0.1% Java_java_util_zip_Inflater_inflateBytes
0 0.0% 100.0% 3064228 0.4% Java_java_util_zip_ZipFile_open
0 0.0% 100.0% 131296 0.0% Java_sun_management_Flag_getFlags
0 0.0% 100.0% 356982 0.0% ZIP_Open
0 0.0% 100.0% 3421211 0.4% ZIP_Unlock
0 0.0% 100.0% 569857981 71.7% __clone
0 0.0% 100.0% 253077 0.0% __dlopen_check
0 0.0% 100.0% 262784 0.0% __pthread_create_2_1
0 0.0% 100.0% 253077 0.0% _dl_catch_error
0 0.0% 100.0% 253077 0.0% _dl_init_internal
0 0.0% 100.0% 253077 0.0% _dl_open
0 0.0% 100.0% 253077 0.0% _dlerror_run
0 0.0% 100.0% 253077 0.0% dl_open_worker
0 0.0% 100.0% 253077 0.0% dlopen_doit
0 0.0% 100.0% 393920 0.0% fork1
0 0.0% 100.0% 1036965 0.1% inflate
0 0.0% 100.0% 569857981 71.7% start_thread
As graph:
I have also used Java Native Memory Tracking tool to pinpoint the leak https://docs.oracle.com/javase/8/docs/technotes/guides/vm/nmt-8.html The NMT reported memory to be leaked under 'Internal' section. The call graph suggests that the JVM_FindSignal is called as a result of start_thread, however, NMT diff tool reported that amount of application threads is almost constant and stays at ~300.
JVM options:
-Xms24920m -Xmx24920m -XX:MaxMetaspaceSize=512m -XX:+AlwaysPreTouch
-XX:+UseG1GC -XX:G1HeapWastePercent=10
-XX:+UseTLAB
-XX:+ScavengeBeforeFullGC -verbose:gc
-XX:+PrintGCDetails
-XX:+PrintGCDateStamps -XX:+PrintTenuringDistribution
-XX:+PrintGCApplicationConcurrentTime
-XX:+PrintGCApplicationStoppedTime
-Djava.rmi.server.hostname=XXXXX
-Dcom.sun.management.jmxremote.port=XXXXX
-Dcom.sun.management.jmxremote.ssl=false
So, JVM_FindSignal has allocated and not released 789 Megabytes of native memory, does anyone has an idea of what JVM_FindSignal does and why would it be continuously allocating memory?
解决方案JVM_FindSignal does not allocate memory at all. And this function is not typically called often at application run-time.
It seems your JDK installation does not include debug symbols, so that jemalloc profiler cannot find the correct function name and just takes the nearest public symbol from libjvm.so. JVM_FindSignal is just one of these random symbols. Other entries in the profile also look wrong. E.g. AsyncGetCallTrace which is accounted for 87.8% also allocates nothing at all.
Installing a separate package with JDK debug symbols might help.
On Debian / Ubuntu:
apt install openjdk-8-dbg
On RHEL / CentOS:
debuginfo-install java-1.8.0-openjdk
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