On Fri, Sep 03, 2010 at 01:02:09PM +0200, Matthias Bolte wrote:
Ah, okay, now I understand what you want to say.
You have two threads A and B. When A runs on its own then it's just fine, but when you add B (that triggers an exception on purpose and ignores it) then A picks it up and reports it. This is the point where thread safety comes to mind.
libvirt stores errors in thread-local-storage. It uses pthread_key_create/pthread_{get,set}specific for this (or TlsAlloc/Tls{Get,Set}Value on Windows).
I think what's happening here is that all your threads in Java share the same thread-local-storage. Therefore, thread A can pickup the error triggered by thread B, that should not happen.
I'm not sure how to fix that.
Looking at the java code, I believe the problem is that the java bindings are *not* using the threadsafe error APIs: In Connect.java /** * call the error handling logic. Should be called after every libvirt call * * @throws LibvirtException */ protected void processError() throws LibvirtException { ErrorHandler.processError(libvirt, VCP); } Which calls into public static void processError(Libvirt libvirt, ConnectionPointer conn) throws LibvirtException { virError vError = new virError(); int errorCode = libvirt.virConnCopyLastError(conn, vError); And virConnCopyLastError is *not* threadsafe: /** * virConnCopyLastError: * @conn: pointer to the hypervisor connection * @to: target to receive the copy * * Copy the content of the last error caught on that connection * * This method is not protected against access from multiple * threads. In a multi-threaded application, always use the * global virGetLastError() API which is backed by thread * local storage. Regards, Daniel -- |: Red Hat, Engineering, London -o- http://people.redhat.com/berrange/ :| |: http://libvirt.org -o- http://virt-manager.org -o- http://deltacloud.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: GnuPG: 7D3B9505 -o- F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 :|