使用Java监控工具出现 Can’t attach to the process
发表于 2015-07-07 | 更新于 2016-11-11 | 分类于 java ， jvm
| 字数统计 507 | 阅读时长 3
问题重现
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 | ➜ jinfo -flags 3032 Attaching to process ID 3032, please wait… Error attaching to process: sun.jvm.hotspot.debugger.DebuggerException: Can ‘t attach to the process sun.jvm.hotspot.debugger.DebuggerException: sun.jvm.hotspot.debugger.DebuggerException: Can’t attach to the process at sun.jvm.hotspot.debugger.linux.LinuxDebuggerLocal $LinuxDebuggerLocalWorkerThread.execute(LinuxDebuggerLocal.java:163) at sun.jvm.hotspot.debugger.linux.LinuxDebuggerLocal.attach(LinuxDebuggerLocal.java:278) at sun.jvm.hotspot.HotSpotAgent.attachDebugger(HotSpotAgent.java:671) at sun.jvm.hotspot.HotSpotAgent.setupDebuggerLinux(HotSpotAgent.java:611) at sun.jvm.hotspot.HotSpotAgent.setupDebugger(HotSpotAgent.java:337) at sun.jvm.hotspot.HotSpotAgent.go(HotSpotAgent.java:304) at sun.jvm.hotspot.HotSpotAgent.attach(HotSpotAgent.java:140) at sun.jvm.hotspot.tools.Tool.start(Tool.java:185) at sun.jvm.hotspot.tools.Tool.execute(Tool.java:118) at sun.jvm.hotspot.tools.JInfo.main(JInfo.java:138) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:483) at sun.tools.jinfo.JInfo.runTool(JInfo.java:108) at sun.tools.jinfo.JInfo.main(JInfo.java:76) Caused by: sun.jvm.hotspot.debugger.DebuggerException: Can ‘t attach to the process at sun.jvm.hotspot.debugger.linux.LinuxDebuggerLocal.attach0(Native Method) at sun.jvm.hotspot.debugger.linux.LinuxDebuggerLocal.access$100(LinuxDebuggerLocal.java:62) at sun.jvm.hotspot.debugger.linux.LinuxDebuggerLocal$1AttachTask.doit(LinuxDebuggerLocal.java:269) at sun.jvm.hotspot.debugger.linux.LinuxDebuggerLocal$LinuxDebuggerLocalWorkerThread.run(LinuxDebuggerLocal.java:138) |
解决办法
| 1 | echo 0 | sudo tee /proc/sys/kernel/yama/ptrace_scope |
再次执行时就可以得到结果了
| 1 2 3 4 5 6 7 | ➜ jinfo -flags 3032 Attaching to process ID 3032, please wait… Debugger attached successfully. Server compiler detected. JVM version is 25.5-b02 Non-default VM flags: -XX:InitialHeapSize=41943040 -XX:MaxHeapSize=536870912 -XX:MaxNewSize=178782208 -XX:M inHeapDeltaBytes=524288 -XX:NewSize=1572864 -XX:OldSize=40370176 -XX:+UseCompressedClassPointers -XX:+UseCompressedOops -XX:+UseParallelGC Command line: -Dosgi.requiredJavaVersion=1.6 -XX:MaxPermSize=256m -Xms40m -Xmx512m |
原因
这是因为新版的Linux系统加入了 ptrace-scope 机制. 这种机制为了防止用户访问当前正在运行的进程的内存和状态, 而一些调试软件本身就是利用 ptrace 来进行获取某进程的内存状态的(包括GDB),所以在新版本的Linux系统, 默认情况下不允许再访问了. 可以临时开启. 如:
| 1 | echo 0 > /proc/sys/kernel/yama/ptrace_scope |
永久写到文件来持久化:
| 1 2 3 4 | emacs /etc/sysctl.d/10-ptrace.conf 添加或修改为以下这一句:(0:允许, 1:不允许) kernel.yama.ptrace_scope = 0 |
