Add the Theano flags allow_gc

theano/compile/mode.py

@@ -63,11 +63,11 @@ def check_equal(x, y):
 predefined_linkers = {
     'py': gof.PerformLinker(),
     'c': gof.CLinker(),
-    'c|py': gof.OpWiseCLinker(allow_gc=True),
+    'c|py': gof.OpWiseCLinker(),
     'c|py_nogc': gof.OpWiseCLinker(allow_gc=False),
     'c&py': gof.DualLinker(checker=check_equal),
-    'vm': gof.vm.VM_Linker(allow_gc=True, use_cloop=False),
-    'cvm': gof.vm.VM_Linker(allow_gc=True, use_cloop=True),
+    'vm': gof.vm.VM_Linker(use_cloop=False),
+    'cvm': gof.vm.VM_Linker(use_cloop=True),
     'vm_nogc': gof.vm.VM_Linker(allow_gc=False, use_cloop=False),
     'cvm_nogc': gof.vm.VM_Linker(allow_gc=False, use_cloop=True),
     }

theano/configdefaults.py

@@ -117,6 +117,16 @@ except OSError:
 
 del dummy_stdin
 
+#Keep the default optimizer the same as the one for the mode FAST_RUN
+AddConfigVar('allow_gc',
+             "Do we default to delete intermediate results during Theano"
+             " function call? Doing so lower the memory requirement, but ask"
+             " that we reallocate memory at the next function call."
+             " This is implemented for the default linker, but not work all"
+             " linker",
+             BoolParam(True),
+             in_c_key=False)
+
 #Keep the default optimizer the same as the one for the mode FAST_RUN
 AddConfigVar('optimizer',
         ("Default optimizer. If not None, will use this linker with the Mode "

theano/gof/cc.py

@@ -1395,8 +1395,10 @@ class OpWiseCLinker(link.LocalLinker):
 
     def __init__(self,
             fallback_on_perform=True,
-            allow_gc=True,
+            allow_gc=None,
             nice_errors=True):
+        if allow_gc is None:
+            allow_gc = config.allow_gc
         self.fgraph = None
         self.fallback_on_perform = fallback_on_perform
         self.nice_errors = nice_errors

theano/gof/vm.py

@@ -469,6 +469,7 @@ class VM_Linker(link.LocalLinker):
         allow_gc - force the virtual machine to clean up unnecessary
             references, in order to allow garbage collection on
             intermediate values during computation of a function.
+            If None use as default the Theano flag allow_gc value.
 
         use_cloop - use the C-based virtual machine if possible
 
@@ -477,6 +478,8 @@ class VM_Linker(link.LocalLinker):
             'node', 'thunk', 'storage_map', and 'compute_map'.
 
         """
+        if allow_gc is None:
+            allow_gc = config.allow_gc
         self.fgraph = None
         self.allow_gc = allow_gc
         self.use_cloop = use_cloop