Description of problem:

RHQ agent running JMX plugin (4.3.0-SNAPSHOT) seems to be sending kill -QUIT to all system Java processes.

If Java is sending its own output to STDOUT, then the shell sends it to a file, then that file becomes corrupted.


Version-Release number of selected component (if applicable):

4.3.0


How reproducible:

Seemingly hard to reproduce. Doesn't seem to happen for all Java processes, oddly enough.

Seems to happen on Linux JDK 1.6.0_30 and _16.

Steps to Reproduce:
1. One way is to run the RHQ command line client as 'rhq' user.
2. Then run agent discovery through the agent command line as root user.

Additional info:

I'm guessing this happens through the attach API, although I am not clear what call does this.

This is from the OpenJDK

src/solaris/classes/sun/tools/attach/LinuxVirtualMachine.java

        // Find the socket file. If not found then we attempt to start the
        // attach mechanism in the target VM by sending it a QUIT signal.
        // Then we attempt to find the socket file again.
        path = findSocketFile(pid);
        if (path == null) {
            File f = createAttachFile(pid);
            try {
                // On LinuxThreads each thread is a process and we don't have the
                // pid of the VMThread which has SIGQUIT unblocked. To workaround
                // this we get the pid of the "manager thread" that is created
                // by the first call to pthread_create. This is parent of all
                // threads (except the initial thread).
                if (isLinuxThreads) {
                    int mpid;
                    try {
                        mpid = getLinuxThreadsManager(pid);
                    } catch (IOException x) {
                        throw new AttachNotSupportedException(x.getMessage());
                    }
                    assert(mpid >= 1);
                    sendQuitToChildrenOf(mpid);
                } else {
                    sendQuitTo(pid);
                }


At the very least, there should be a way to disable this discovery mechanism or not attempt to attach to processes not explicitly requested.