What does it mean if the JVM is paused?

Question

When my application starts. I received a message:

Ping: Timed out waiting for signal from JVM. The JVM was launched with debug options so this may be because the JVM is currently suspended by a debugger. Any future timeouts during this JVM invocation will be silently ignored. 

What does it mean? Does it seem to block any web request from outside? because when I upload a file to it, it failed. help me.

Answer 1

When debugging code, breakpoints are usually set in it to break program execution at some point. When the JVM encounters such a breakpoint, it pauses execution and expects the debugger to move on (step in / step over / step out / etc).

If you have a UI debugger (for example, Eclipse) connected to your process, you can control the execution flow from there, view the values ​​of variables, etc.

The message you see simply says that the timeout you received may simply be the result of such a situation and shown by the Java Service Wrapper, as described here :

Wrapper will decide that the JVM uses a debugger if the wrapper.java.command property is set to "jdb" or "jdb.exe" or if one of the wrapper.java.additional properties is set. <n> is set to -Xdebug.

So it seems that you are launching your application using Java Service Wrapper in debug mode, and when the timeout expires, it warns you with an attached message.

Answer 2

JVM debugging options allow you to connect to the JVM and execute code (remote Google java debugging for more information). This basically means that code execution can be suspended remotely and monitored (execute one statement at a time, check the values ​​of variables, etc.). Although very useful, it can, of course, interfere with the normal operation of a piece of software. If you are not going to start the JVM in debug mode, try to find out what settings and delete it (it can be in JAVA_OPTS (environment variable), or it can be in your startup script or whatever you want to start the JVM. You are looking for a line that It looks something like -Xdebug -Xrunjdwp:server=y, transport=dt_socket,address=#number#, suspend=n . Remove all this, comment or no matter where it is installed, and then restart the JVM.

Answer 3

What does it mean?

The message comes from Java Wrapper . The wrapper attempted to ping the JVM and received no response. Most likely, this means that you are debugging the JVM and pausing it. While the JVM is paused, it cannot respond to external requests of any type. All threads are frozen ...

Does it seem to block any web request from outside? because when I upload a file to it, it failed. help me

Yes, that would do it if you paused the JVM. Unpause the JVM, and it should start responding again.

Please note: if you run the application from the IDE in debug mode, the JVM may start in a paused state ... depending on the IDE / launch settings.

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The only other explanation I can think of is that you might have problems setting up your network or virtual network (for example, packet filters or virtual network routing) that cause large-scale loss of network packets.