Threads in thread pool getting hung on ppc64le

[npanpaliya]

Hi,

We have built torch on ppc64le. And while testing it, we found a problem wherein threads get hung if we have a thread pool containing higher number of threads say 16 (at times, even with 8). I guess something similar to (#62, OR #16)

Here is our test case -

local Threads = require 'threads'
nthreads = 64
Threads.serialization('threads.sharedserialize')
thrds = Threads(nthreads,
         function()  print('Starting thread ') end,
         function()  require 'image' end
      );
thrds:synchronize()
print "Done"

Some of my observations -

• After debugging using gdb, I saw all of the threads are sitting in pthread_cond_wait function.
• Also, in above example, I also observed that if I remove "require 'image'", it even works with 64 threads. So, I think either it has to be something with the memory as well, as require image loads a bunch of stuff and probably eating up the memory. But really not sure.
• Above test works well on x86 even with 64 threads.

Any help would be really appreciated.

[npanpaliya]

We got this issue fixed by building torch using the latest Advanced Toolchain to 10.0 which has gcc 6.2.1 and glibc 2.24.