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From: Siegfried Goeschl <siegfried.goeschl@it20one.com>
Message-Id: <94F3748D-83C4-4E3E-9489-F0570CF779DD@it20one.com>
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Subject: Re: Proper use of Executors
Date: Sun, 28 May 2017 21:41:01 +0200
In-Reply-To: <CACK3WSf5JHRAkvc7fHnmLm3WTheNVTFenSaH+2vxvP9Pes5VdA@mail.gmail.com>
Cc: cgamache@gmail.com
To: Commons Users List <user@commons.apache.org>
References: <CACK3WSf5JHRAkvc7fHnmLm3WTheNVTFenSaH+2vxvP9Pes5VdA@mail.gmail.com>
archived-at: Sun, 28 May 2017 19:41:20 -0000

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Hi Chris,

there are couple of things to consider

* You are using a PumpStreamHander but the STDERR is not consumed. Each =
process has an internal buffer (size depends on the OS) and when the =
buffer is full any write to STDERR is blocked
* That could happen if the process being executed actually writes some =
error messages :-)
* Are you 100% sure that the processes will terminate? See =
ExecuteWatchdog
* You might habe a look at ProcessDestroyer to cleanup during shutdown

Thanks in advance,

Siegfried Goeschl


> On 27 May 2017, at 14:27, Chris Gamache <cgamache@gmail.com> wrote:
>=20
> Hi all,
>=20
> I'm using org.apache.commons:commons-exec:1.3 on Java 8.
>=20
> I'm having an issue where my Tomcat server is bleeding out hundreds of
> threads and all of the memory in the form of Executors that I'm =
running but
> don't seem to be closing down ... When the server finally grinds to a =
halt
> I have to restart. When I do it looks like this at shutdown time:
>=20
> <snip>
>=20
> 27-May-2017 07:56:21.631 WARNING [localhost-startStop-11]
> =
org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads =
The
> web application [ROOT##000252] appears to have started a thread named =
[Exec
> Default Executor] but has failed to stop it. This is very likely to =
create
> a memory leak. Stack trace of thread:
> java.lang.Object.wait(Native Method)
> java.lang.Object.wait(Object.java:502)
> java.lang.UNIXProcess.waitFor(UNIXProcess.java:396)
> =
org.apache.commons.exec.DefaultExecutor.executeInternal(DefaultExecutor.ja=
va:364)
> =
org.apache.commons.exec.DefaultExecutor.access$200(DefaultExecutor.java:48=
)
> =
org.apache.commons.exec.DefaultExecutor$1.run(DefaultExecutor.java:200)
> java.lang.Thread.run(Thread.java:745)
>=20
> 27-May-2017 07:56:21.633 WARNING [localhost-startStop-11]
> =
org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads =
The
> web application [ROOT##000252] appears to have started a thread named =
[Exec
> Stream Pumper] but has failed to stop it. This is very likely to =
create a
> memory leak. Stack trace of thread:
> java.io.FileInputStream.readBytes(Native Method)
> java.io.FileInputStream.read(FileInputStream.java:255)
> java.io.BufferedInputStream.fill(BufferedInputStream.java:246)
> java.io.BufferedInputStream.read1(BufferedInputStream.java:286)
> java.io.BufferedInputStream.read(BufferedInputStream.java:345)
> java.io.FilterInputStream.read(FilterInputStream.java:107)
> org.apache.commons.exec.StreamPumper.run(StreamPumper.java:107)
> java.lang.Thread.run(Thread.java:745)
>=20
> </snip>
>=20
> And my thread dump is a mile long.
>=20
> I am certainly willing to concede I'm Doing It Wrong(tm) ... Here's =
the
> relevant code. It is called from a regular method in a regular class,
> nothing fancy:
>=20
> CommandLine cmdLine =3D CommandLine.parse(command.toString());
> DefaultExecutor executor =3D new DefaultExecutor();
> PumpStreamHandler esh =3D new PumpStreamHandler(os,null,is);
> executor.setStreamHandler(esh);
> executor.execute(cmdLine);
>=20
> `is` and `os` are passed in on the constructor. Their opens and closes =
are
> managed well and cleaned up on the outside of this class...
> Are there further steps I'm missing to ensure the threads I'm creating =
are
> getting shut down properly and the resources they are using are being
> returned?
>=20
> Any help is much appreciated.


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