Merge pull request #798 from nouiz/vm_gc_follow_up

theano/configdefaults.py

@@ -339,6 +339,17 @@ AddConfigVar('warn.gpu_set_subtensor1',
         BoolParam(warn_default('0.6')),
         in_c_key=False)
 
+AddConfigVar('warn.vm_gc_bug',
+        "There was a bug that existed in the default Theano configuration"
+        " just in the development version between July 5 2012"
+        " and July 30 2012. This was not in a released version."
+        " If your code was affected by this bug, a warning"
+        " will be printed during the code execution if you use the"
+        "`linker=vm,vm.lazy=True,warn.vm_gc_bug=True` Theano flags."
+        "This warning is disabled by default as the bug was not released.",
+        BoolParam(False),
+        in_c_key=False)
+
 AddConfigVar('compute_test_value',
         ("If 'True', Theano will run each op at graph build time, using "
          "Constants, SharedVariables and the tag 'test_value' as inputs "

theano/gof/tests/test_vm.py

@@ -306,3 +306,9 @@ def test_vm_gc():
     f = theano.function([theano.In(x, mutable=True)], [p + 1, p + 2],
                         mode=mode)
     f([1, 2, 3])
+
+    p = RunOnce()(x)
+    pp = p + p
+    f = theano.function([x], [pp + pp],
+                        mode=mode)
+    f([1, 2, 3])

theano/gof/vm.py

@@ -3,10 +3,12 @@ VMs that run Theano graph computations.
 A VM is not actually different from a Linker, we just decided
 VM was a better name at some point
 """
+import link
 import logging
 import sys
 import time
-import link
+import warnings
+
 from theano.gof.python25 import all
 
 import theano
@@ -396,6 +398,19 @@ class Stack(VM):
                                     #recomputed! This can cause wrong value
                                     #with some combiation of inplace op.
                                     compute_map[i][0] = 2
+                                    if (config.warn.vm_gc_bug and
+                                        current_apply in apply_stack and
+                                        getattr(current_apply.op,
+                                                'destroy_map',
+                                                False)):
+                                        warnings.warn(
+        "There was a bug that existed in the default Theano configuration"
+        " just in the development version between July 5 2012"
+        " and July 30 2012. This was not in a released version."
+        "The bug was affecting this script.",
+        #The stack level is not good when inside a Scan.
+        stacklevel=3
+                                        )
                 elif not computed_ins:
                     # -- Non-lazy case, need inputs
                     apply_stack.append(current_apply)
@@ -505,10 +520,11 @@ class VM_Linker(link.LocalLinker):
             the virtual machine.  It will be called with four arguments called
             'node', 'thunk', 'storage_map', and 'compute_map'.
 
-        lazy - Useful only when use_cloop is False. When lazy is None, auto
+        lazy - Useful only when use_cloop is False. When lazy is None, use the
+            theano flag vm.lazy value. Then if we have a None(default) we auto
             detect if lazy evaluation is needed and use the apropriate
-            version. If lazy it True/False, force the version used between
-            Loop/LoopGC and Stack.
+            version. If lazy is True or False, we force the version used
+            between Loop/LoopGC and Stack.
 
         """
         if allow_gc is None:
@@ -712,6 +728,8 @@ class VM_Linker(link.LocalLinker):
             assert c0 == sys.getrefcount(node_n_inputs)
         else:
             lazy = self.lazy
+            if lazy is None:
+                lazy = config.vm.lazy
             if lazy is None:
                 lazy = not all([(not th.lazy) for th in thunks])
             if not lazy:

theano/misc/do_nightly_build

@@ -68,8 +68,8 @@ THEANO_FLAGS=${FLAGS},mode=FAST_RUN,floatX=float32 ${NOSETESTS} ${ARGS}
 echo "Number of elements in the compiledir:"
 ls ${COMPILEDIR}|wc -l
 
-echo "Executing nosetests with mode=vm,vm.lazy=True,floatX=float32"
-THEANO_FLAGS=${FLAGS},mode=vm,vm.lazy=True,floatX=float32 ${NOSETESTS} ${ARGS}
+echo "Executing nosetests with linker=vm,vm.lazy=True,floatX=float32"
+THEANO_FLAGS=${FLAGS},linker=vm,vm.lazy=True,floatX=float32 ${NOSETESTS} ${ARGS}
 echo "Number of elements in the compiledir:"
 ls ${COMPILEDIR}|wc -l