use available procs for process

src/megahit

@@ -552,12 +552,12 @@ def check_and_correct_option():
         raise Usage('--low-local-ratio should be in (0, 0.5].')
     if opt.cleaning_rounds <= 0:
         raise Usage('--cleaning-rounds must be >= 1')
-    if opt.num_cpu_threads > multiprocessing.cpu_count():
-        logger.warning('Maximum number of available CPU thread is %d.' % multiprocessing.cpu_count())
-        logger.warning('Number of thread is reset to the %d.' % multiprocessing.cpu_count())
-        opt.num_cpu_threads = multiprocessing.cpu_count()
+    if opt.num_cpu_threads > len(os.sched_getaffinity(0)):
+        logger.warning('Maximum number of available CPU thread is %d.' % len(os.sched_getaffinity(0)))
+        logger.warning('Number of thread is reset to the %d.' % len(os.sched_getaffinity(0)))
+        opt.num_cpu_threads = len(os.sched_getaffinity(0))
     if opt.num_cpu_threads == 0:
-        opt.num_cpu_threads = multiprocessing.cpu_count()
+        opt.num_cpu_threads = len(os.sched_getaffinity(0))
     if opt.prune_depth < 0 and opt.prune_level < 3:
         opt.prune_depth = opt.min_count
     if opt.bubble_level < 0: