Andi Vajda <va...@apache.org> wrote:
>
> On Mar 10, 2009, at 10:02, Bill Janssen <jans...@parc.com> wrote:
>
> > Andi Vajda <va...@apache.org> wrote:
> >
> >> On Mon, 9 Mar 2009, Bill Janssen wrote:
> >>
> >>> I just spent some time tracking down a core dump in a big Python
> >>> program, in PyLucene, till I figured out that the thread making
> >>> the call
> >>> had never been registered as a Java thread (the code at some interim
> >>> calling frame changed till it suddenly was calling into Java).
> >>>
> >>> Is there some way to make that throw an exception rather than a
> >>> segfault
> >>> -- "Attempt to call into Java from a non-Java thread"? That would
> >>> be
> >>> really useful.
> >>
> >> Yes, there is a way but I'm not sure it's too efficient. If the
> >> JCCEnv::get_vm_env() method returns NULL it can mean that your thread
> >> wasn't attached to the VM. More precisely, if you didn't attach your
> >> thread, this method must be returning NULL.
> >>
> >> inline JNIEnv *get_vm_env()
> >> {
> >> return (JNIEnv *) pthread_getspecific(VM_ENV);
> >> }
> >>
> >> The problem is that this method is called a _lot_ and adding code
> >> checking the value and raising an exception would be costly for this
> >> currently short inlined function.
> >>
> >> It would be ideal if a less frequently called, but nonetheless
> >> indispensable, piece of code could catch that problem instead of
> >> adding a check at that low a level. I haven't found one yet. Another
> >> way to improve this (and the similar problem of missing the call to
> >> initVM()) would be to have a better debug mode where the check would
> >> be then compiled in.
> >
> > So, it sounds like I could add to my code a call to lucene.getVMEnv().
> > If it returns None, it's a bad thread, and I shouldn't make any other
> > calls to lucene in it. That way I could control the efficiency
> > concerns
> > in application code. Right?
>
> I'm not sure (not near my computer at the moment) but if you are
> prepared to call a piece of code, why not call attachCurrentThread()
> then ? it's supposed to be a nop if it was called before.
>
> Andi..
Well, it's not supposed to happen, so it indicates a bug in the program
flow, and I'd just as soon raise an exception and catch that bug, not
swallow it.
Bill
