在Java中,有没有一种方法可以在不抛出异常的情况下转储堆栈跟踪?

我正在考虑为我的Java应用程序创建一个调试工具。

我想知道是否有可能得到一个堆栈跟踪,就像Exception.printStackTrace(),但实际上没有抛出一个异常?

我的目标是,在任何给定的方法中,转储堆栈以查看谁是方法调用方。

92186 次浏览

Yes, simply use

Thread.dumpStack()

You can get a stack trace like this:

Throwable t = new Throwable();
t.printStackTrace();

If you want to access the frame, you can use t.getStackTrace() to get an array of stack frames.

Be aware that this stacktrace (just like any other) may be missing some frames if the hotspot compiler has been busy optimizing things.

You can also try Thread.getAllStackTraces() to get a map of stack traces for all the threads that are alive.​​​​​​

If you want the trace for just the current thread (rather than all the threads in the system, as Ram's suggestion does), do:

Thread.currentThread().getStackTrace()

To find the caller, do:

private String getCallingMethodName() {
StackTraceElement callingFrame = Thread.currentThread().getStackTrace()[4];
return callingFrame.getMethodName();
}

And call that method from within the method that needs to know who its caller is. However, a word of warning: the index of the calling frame within the list could vary according to the JVM! It all depends on how many layers of calls there are within getStackTrace before you hit the point where the trace is generated. A more robust solution would be to get the trace, and iterate over it looking for the frame for getCallingMethodName, then take two steps further up to find the true caller.

HPROF Java Profiler

You don't even have to do this in the code. You can attach the Java HPROF to your process and at any point hit Control-\ to output heap dump, running threads, etc . . . without mucking up your application code. This is a bit outdated, Java 6 comes with the GUI jconsole, but I still find HPROF to be very useful.

You can also send a signal to the JVM to execute Thread.getAllStackTraces() on a running Java process by sending a QUIT signal to the process.

On Unix/Linux use:

kill -QUIT process_id, where process_id is the process number of your Java program.

On Windows, you can press Ctrl-Break in the application, although you usually won't see this unless you're running a console process.

JDK6 introduced another option, the jstack command, which will display the stack from any running JDK6 process on your computer:

jstack [-l] <pid>

These options are very useful for applications which are running in a production environment and cannot be modified easily. They're especially useful for diagnosing runtime deadlocks or performance problems.

http://java.sun.com/developer/technicalArticles/Programming/Stacktrace/ http://java.sun.com/javase/6/docs/technotes/tools/share/jstack.html

Notice that Thread.dumpStack() actually throws an exception:

new Exception("Stack trace").printStackTrace();

If you need capture output

StringWriter sw = new StringWriter();
new Throwable("").printStackTrace(new PrintWriter(sw));
String stackTrace = sw.toString();

Java 9 introduced the StackWalker and supporting classes for walking the stack.

Here are a few snippets from the Javadoc:

The walk method opens a sequential stream of StackFrames for the current thread and then applies the given function to walk the StackFrame stream. The stream reports stack frame elements in order, from the top most frame that represents the execution point at which the stack was generated to the bottom most frame. The StackFrame stream is closed when the walk method returns. If an attempt is made to reuse the closed stream, IllegalStateException will be thrown.

...

  1. To snapshot the top 10 stack frames of the current thread,

    List<StackFrame> stack = StackWalker.getInstance().walk(s ->
    s.limit(10).collect(Collectors.toList()));
    

The answer by Rob Di Marco is by far the best if you are happy to output to stderr.

If you want to capture to a String, with new lines as per a normal trace, you could do this:

Arrays.toString(Thread.currentThread().getStackTrace()).replace( ',', '\n' );