exec hangs when program not found about ch.vorburger.exec

[vorburger]

@shague your (and @trozet's ...) [1] looks about right, I guess. But there does indeed seem to be bug related to some sort of deadlock when starting a non existant executable - I can reproduce the "hang" with this in ManagedProcessTest :

    @Test(expected = ManagedProcessException.class)
    public void startForMustFailForWrongExecutable() throws Exception {
        ManagedProcess p = new ManagedProcessBuilder("someExec").build();
        p.start();
    }

I'll debug this further when I have a minute, and fix it.

[vorburger]

I've just deployed a 3.1.1 release with this fix to Maven central; it should be available from there shortly.

[shague]

Thanks for the fix. It works well.

[gsylvie]

3.1.1 still hanging for me in this scenario.

import ch.vorburger.exec.ManagedProcess;
import ch.vorburger.exec.ManagedProcessBuilder;
public class Test {
    public static void main(String[] args) throws Exception {
        ManagedProcessBuilder mpb = new ManagedProcessBuilder("cmd-does-not-exist");
        ManagedProcess p = mpb.build();
        p.start();
    }
}

Running "kill -3" against the hung process shows this culprit:

"Exec Default Executor" #19 prio=5 os_prio=0 tid=0x00007ff504464000 nid=0xb69a in Object.wait() [0x00007ff4de4fa000]
   java.lang.Thread.State: WAITING (on object monitor)
	at java.lang.Object.wait(Native Method)
	- waiting on <0x000000071ae65210> (a org.apache.commons.exec.ExecuteWatchdog)
	at java.lang.Object.wait(Object.java:502)
	at org.apache.commons.exec.ExecuteWatchdog.ensureStarted(ExecuteWatchdog.java:229)
	at org.apache.commons.exec.ExecuteWatchdog.isWatching(ExecuteWatchdog.java:196)
	- locked <0x000000071ae65210> (a org.apache.commons.exec.ExecuteWatchdog)
	at ch.vorburger.exec.ManagedProcess.notifyProcessHalted(ManagedProcess.java:374)
	at ch.vorburger.exec.LoggingExecuteResultHandler.onProcessFailed(LoggingExecuteResultHandler.java:57)
	at ch.vorburger.exec.CompositeExecuteResultHandler.onProcessFailed(CompositeExecuteResultHandler.java:63)
	at org.apache.commons.exec.DefaultExecutor$1.run(DefaultExecutor.java:205)
	at java.lang.Thread.run(Thread.java:748)

[gsylvie]

Note: The main thread is terminating properly (and throwing the exception as expected). But seems a background thread is being created and never terminated - causing the "java" process on my system to hang.

[vorburger]

@gsylvie do you want to check if #96 from @cardamon might fix this problem?

[vorburger]

@mosesn do you have any interest to further dig into if this is still a bug that needs to be fixed?

[vorburger]

@gsylvie you are right. I can reproduce this easily in #188, using your example.

However, the likely culprit appears to more something in https://commons.apache.org/proper/commons-exec/ than in this project?

It's probably worth first checking if #179 already fixes this by chance...

[vorburger]

It's probably worth first checking if #179 already fixes this by chance...

Looks like it does! I should definitely get #179 into #105, in that case...