Only thing I can suggest is to place a thread lock around the call to
comm_spawn so that only one thread at a time can execute that
function. The call to mpi_init_thread is fine - you just need to
explicitly protect the call to comm_spawn.
On Sep 17, 2009, at 7:44 PM, Ashika Umanga Umagiliya wrote:
HI Jeff, Ralph,
Yes, I call MPI_COMM_SPAWN in multiple threads simultaneously.
Because I need to expose my parallel algorithm as a web service, I
need multiple clients connect and execute my logic as same time(ie
mutiple threads).
For each client , a new thread is created (by Web service framework)
and inside the thread,MPI_Init_Thread() is called if the MPI hasnt
been initialized.
The the thread calls MPI_COMM__SPAWN and create new processes.
So ,if this is the case isn't there any workarounds ?
Thanks in advance,
umanga
Jeff Squyres wrote:
On Sep 16, 2009, at 9:53 PM, Ralph Castain wrote:
Only the obvious, and not very helpful one: comm_spawn isn't thread
safe at this time. You'll need to serialize your requests to that
function.
This is likely the cause of your issues if you are calling
MPI_COMM_SPAWN in multiple threads simultaneously. Can you verify?
If not, we'll need to dig a little deeper to figure out what's
going on. But Ralph is right -- read up on the THREAD_MULTIPLE
constraints (check the OMPI README file) to see if that's what's
biting you.
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