Test if g++ support openmp or not.

theano/__init__.py

@@ -106,6 +106,9 @@ if config.device.startswith('gpu') or config.init_gpu_device.startswith('gpu'):
         import theano.sandbox.cuda.tests.test_driver
         theano.sandbox.cuda.tests.test_driver.test_nvidia_driver1()
 
+
+import configdefaults_late
+
 # Use config.numpy to call numpy.seterr
 import numpy
 if config.numpy.seterr_all == 'None':

theano/configdefaults.py

@@ -16,42 +16,6 @@ AddConfigVar('floatX',
         EnumStr('float64', 'float32'),
         )
 
-#http://pyprocessing.berlios.de/
-#True if the environment variable OMP_NUM_THREADS!=1 or
-#if we detect more then 1 CPU core. Otherwise False.
-default_openmp = True
-var = os.getenv('OMP_NUM_THREADS', None)
-if var:
-    try:
-        int(var)
-    except ValueError:
-        raise TypeError("The environment variable OMP_NUM_THREADS"
-                        " should be a number, got '%s'." % var)
-    else:
-        default_openmp = not int(var) == 1
-else:
-    count = cpuCount()
-    if count == -1:
-        _logger.warning("We are not able to detect the number of CPU cores."
-                        " We disable openmp by default. To remove this"
-                        " warning, set the environment variable"
-                        " OMP_NUM_THREADS to the number of threads you"
-                        " want theano to use.")
-    default_openmp = count > 1
-
-AddConfigVar('openmp',
-             "Enable (or not) parallel computation on the CPU with OpenMP. "
-             "This is the default value used when creating an Op that "
-             "supports OpenMP parallelization. It is preferable to define it "
-             "via the Theano configuration file ~/.theanorc or with the "
-             "environment variable THEANO_FLAGS. Parallelization is only "
-             "done for some operations that implement it, and even for "
-             "operations that implement parallelism, each operation is free "
-             "to respect this flag or not.",
-             BoolParam(default_openmp),
-             in_c_key=False,
-         )
-
 AddConfigVar('cast_policy',
         "Rules for implicit type casting",
         EnumStr('custom', 'numpy+floatX',
@@ -123,6 +87,7 @@ AddConfigVar('mode',
                 'FAST_COMPILE', 'PROFILE_MODE', 'DEBUG_MODE'),
         in_c_key=False)
 
+gxx_avail = True
 # Test whether or not g++ is present: disable C code if it is not.
 # Using the dummy file descriptor below is a workaround for a crash experienced
 # in an unusual Python 2.4.4 Windows environment with the default stdin=None.
@@ -148,6 +113,7 @@ except OSError:
             'optimized C-implementations (for both CPU and GPU) and will '
             'default to Python implementations. Performance will be severely '
             'degraded.')
+    gxx_avail = False
 
 del dummy_stdin
 

theano/configdefaults_late.py

+"""
+This file define Theano flags, but we define them later in the import order.
+
+This is needed as we need to have parsed the previous
+"""
+
+import os
+import logging
+import subprocess
+
+import theano
+from theano.configparser import (
+        AddConfigVar, BoolParam, ConfigParam, EnumStr, IntParam,
+        TheanoConfigParser)
+from theano.misc.cpucount import cpuCount
+
+_logger = logging.getLogger('theano.configdefaults_late')
+
+config = TheanoConfigParser()
+
+#http://pyprocessing.berlios.de/
+#True if the environment variable (OMP_NUM_THREADS!=1 or
+#if we detect more then 1 CPU core) and g++ support OpenMP
+#Otherwise False.
+default_openmp = True
+
+#Test if the env variable is set
+var = os.getenv('OMP_NUM_THREADS', None)
+if var:
+    try:
+        int(var)
+    except ValueError:
+        raise TypeError("The environment variable OMP_NUM_THREADS"
+                        " should be a number, got '%s'." % var)
+    else:
+        default_openmp = not int(var) == 1
+else:
+    #Check the number of cores availables.
+    count = cpuCount()
+    if count == -1:
+        _logger.warning("We are not able to detect the number of CPU cores."
+                        " We disable openmp by default. To remove this"
+                        " warning, set the environment variable"
+                        " OMP_NUM_THREADS to the number of threads you"
+                        " want theano to use.")
+    default_openmp = count > 1
+
+dummy_stdin = open(os.devnull)
+
+if default_openmp and theano.configdefaults.gxx_avail:
+    #check if g++ support openmp. We need to compile a file as the EPD
+    #version have openmp enabled in the specs file but do not include
+    #the OpenMP files.
+    try:
+        code = """
+        #include <omp.h>
+int main( int argc, const char* argv[] )
+{
+        int res[10];
+
+        for(int i=0; i < 10; i++){
+            res[i] = i;
+        }
+}
+        """
+        p = os.path.join(config.compiledir, 'test_omp.c')
+        f = open(p, 'w')
+        f.write(code)
+        f.close()
+        p = subprocess.Popen(['g++', '-fopenmp', p], stdout=subprocess.PIPE,
+                         stderr=subprocess.PIPE,
+                         stdin=dummy_stdin.fileno())
+        p.wait()
+        if p.returncode != 0:
+            default_openmp = False
+    except OSError, e:
+        default_openmp = False
+
+
+del dummy_stdin
+
+
+AddConfigVar('openmp',
+             "Enable (or not) parallel computation on the CPU with OpenMP. "
+             "This is the default value used when creating an Op that "
+             "supports OpenMP parallelization. It is preferable to define it "
+             "via the Theano configuration file ~/.theanorc or with the "
+             "environment variable THEANO_FLAGS. Parallelization is only "
+             "done for some operations that implement it, and even for "
+             "operations that implement parallelism, each operation is free "
+             "to respect this flag or not.",
+             BoolParam(default_openmp),
+             in_c_key=False,
+         )