问题
We use jstack on servers to detect if java apps are getting deadlocked. It's not working on one of our Linux servers. I think O/S version is:
$cat /etc/issue.net
Red Hat Enterprise Linux Server release 5.6 (Tikanga)
Kernel \r on an \m
Java version running on server:
java version "1.6.0_24"
Java(TM) SE Runtime Environment (build 1.6.0_24-b07)
Java HotSpot(TM) 64-Bit Server VM (build 19.1-b02, mixed mode)
When I try:
jstack 19114
I get:
19114: Unable to open socket file: target process not responding or HotSpot VM not loaded
The -F option can be used when the target process is not responding
When I try:
jstack -F 19114
I get:
Attaching to process ID 19114, please wait...
Debugger attached successfully.
Deadlock Detection:
No deadlocks found.
Thread 19180: (state = BLOCKED)
Error occurred during stack walking:
sun.jvm.hotspot.debugger.DebuggerException: sun.jvm.hotspot.debugger.DebuggerException: get_thread_regs failed for a lwp
at sun.jvm.hotspot.debugger.linux.LinuxDebuggerLocal$LinuxDebuggerLocalWorkerThread.execute(LinuxDebuggerLocal.java:152)
at sun.jvm.hotspot.debugger.linux.LinuxDebuggerLocal.getThreadIntegerRegisterSet(LinuxDebuggerLocal.java:466)
at sun.jvm.hotspot.debugger.linux.LinuxThread.getContext(LinuxThread.java:65)
at sun.jvm.hotspot.runtime.linux_amd64.LinuxAMD64JavaThreadPDAccess.getCurrentFrameGuess(LinuxAMD64JavaThreadPDAccess.java:92)
at sun.jvm.hotspot.runtime.JavaThread.getCurrentFrameGuess(JavaThread.java:256)
at sun.jvm.hotspot.runtime.JavaThread.getLastJavaVFrameDbg(JavaThread.java:218)
at sun.jvm.hotspot.tools.StackTrace.run(StackTrace.java:76)
at sun.jvm.hotspot.tools.StackTrace.run(StackTrace.java:45)
at sun.jvm.hotspot.tools.JStack.run(JStack.java:60)
at sun.jvm.hotspot.tools.Tool.start(Tool.java:221)
at sun.jvm.hotspot.tools.JStack.main(JStack.java:86)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at sun.tools.jstack.JStack.runJStackTool(JStack.java:118)
at sun.tools.jstack.JStack.main(JStack.java:84)
Caused by: sun.jvm.hotspot.debugger.DebuggerException: get_thread_regs failed for a lwp
at sun.jvm.hotspot.debugger.linux.LinuxDebuggerLocal.getThreadIntegerRegisterSet0(Native Method)
at sun.jvm.hotspot.debugger.linux.LinuxDebuggerLocal.access$800(LinuxDebuggerLocal.java:51)
at sun.jvm.hotspot.debugger.linux.LinuxDebuggerLocal$1GetThreadIntegerRegisterSetTask.doit(LinuxDebuggerLocal.java:460)
at sun.jvm.hotspot.debugger.linux.LinuxDebuggerLocal$LinuxDebuggerLocalWorkerThread.run(LinuxDebuggerLocal.java:127)
Anyone know what is causing this?
回答1:
It is required to run jstack as the same user that started the java process. This resolves the above stacktrace error. See this posting: jstack thread dump error: get_thread_regs failed for a lwp for more detail. As soon as I sudoed the jstack command, the error disappeared.
回答2:
The syntax is simply:
sudo -u USERID jstack PID
Example:
sudo -u tomcat7 jstack 2498
回答3:
Try using kill -3 <pid>
instead to get the stacktrace of your VM.
回答4:
Can use a jsp that gives you similar output instead.
Following jsp prints the thread stack info to screen but you could change the output to a file as well or use in a regular POJO class.
<%@ page import="java.util.*" %><%
Map<Thread,StackTraceElement[]> map = Thread.getAllStackTraces();
Set tt = map.keySet();
Iterator<Thread> ti = tt.iterator();
Thread thrd = null;
final String br = "<" + "br" + ">";//website does not parse it
try{
int cnt = 1;
StackTraceElement[] st = null;
while(ti.hasNext() ){
thrd = ti.next();
out.print(br + "<" + "hr" + ">" + br + cnt + " \"" + thrd.getName());
out.println("\", priority :" + thrd.getPriority() + ", state :" + thrd.getState());
out.print(", id :" + thrd.getId() + ", hex :" + Long.toHexString(thrd.getId()) );
out.print(" alive :" + thrd.isAlive() + ", daemon :" + thrd.isDaemon() );
out.print(" interrupted :" + thrd.isInterrupted() + ", daemon :" + thrd.isDaemon() );
out.print(".\n" + br);
st = thrd.getStackTrace();
for(int sti = 0; sti < st.length; sti++){
out.println(br + " " + st[sti].getClassName() + "." + st[sti].getMethodName());
out.println("(" + st[sti].getFileName());
if(st[sti].getLineNumber() < 1){
out.print("Native method");
}else{
out.print(":" + st[sti].getLineNumber());
}
out.println(")");
}
out.println("");
cnt++;
}
}catch(Exception e){
out.println(br + "err " + e + br);
}
%>
Sample output:
121 "Thread-40", priority :6, state :WAITING , id :134, hex :86 alive :true, daemon :false interrupted :false, daemon :false.
java.lang.Object.wait (Object.java Native method)
java.lang.Object.wait (Object.java :485)
org.jpos.iso.ISOMUX$Receiver.run (ISOMUX.java :326)
java.lang.Thread.run (Thread.java :662)122 "Thread-48", priority :5, state :TIMED_WAITING , id :142, hex :8e alive :true, daemon :false interrupted :false, daemon :false.
java.lang.Thread.sleep (Thread.java Native method)
org.jpos.apps.qsp.QSP.monitorConfigFile (QSP.java :301)
org.jpos.apps.qsp.QSP.run (QSP.java :346)
java.lang.Thread.run (Thread.java :662)
来源:https://stackoverflow.com/questions/8145840/jstack-not-working-on-server