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.
Andi..
