Remove var op deps in imperative mode

test=develop

paddle/fluid/framework/block_desc.cc

@@ -159,6 +159,7 @@ void BlockDesc::RemoveOpInternal(const OpDesc *op_desc) {
   for (auto it = ops_.begin(); it != ops_.end(); ++it) {
     if (it->get() == op_desc) {
       ops_.erase(it);
+      break;
     }
   }
 }

paddle/fluid/imperative/layer.cc

@@ -158,8 +158,9 @@ class Autograd {
       for (auto it : candidate->pre_ops_) {
         for (OpBase* pre_op : it.second) {
           if (!pre_op) continue;
-          VLOG(5) << "op dep " << candidate->op_desc_->Type() << " <---- "
-                  << it.first << " <---- " << pre_op->op_desc_->Type();
+          VLOG(5) << "op dep " << candidate->op_desc_->Type() << " "
+                  << candidate->trace_id_ << " <---- " << it.first << " <---- "
+                  << pre_op->op_desc_->Type() << " " << pre_op->trace_id_;
           if (visited.find(pre_op) == visited.end()) {
             visited.insert(pre_op);
             queue.push_back(pre_op);

python/paddle/fluid/framework.py

@@ -723,7 +723,9 @@ class Operator(object):
                 out_arg_names = []
                 for arg in out_args:
                     out_arg_names.append(cpt.to_text(arg.name))
-                    arg.op = self
+                    # TODO(minqiyang): could we remove variable's op in static mode?
+                    if not _in_imperative_mode():
+                        arg.op = self
                 self.desc.set_output(out_proto.name, out_arg_names)
 
         if op_attrs is not None:

python/paddle/fluid/imperative/tracer.py

@@ -24,6 +24,10 @@ __all__ = ['Tracer']
 
 
 def release_op(op):
+    import gc
+    assert len(
+        gc.get_referrers(framework._imperative_tracer()._ops[
+            op._trace_id])) == 1
     del framework._imperative_tracer()._ops[op._trace_id]
 
 
@@ -41,7 +45,6 @@ class Tracer(core.Tracer):
     def trace_op(self, op, stop_gradient=False):
         # record op's trace id
         op.iop._trace_id = self._trace_id
-        self._trace_id += 1
 
         # trace op and save it
         backward_refs = self.trace(op.iop, op.inputs, op.outputs, op.block.desc,
@@ -49,6 +52,7 @@ class Tracer(core.Tracer):
                                    stop_gradient)
 
         if not stop_gradient:
+            self._trace_id += 1
             self._ops[op.iop._trace_id] = op
 
             # register backward hooks and variables if needed

python/paddle/fluid/initializer.py

@@ -19,6 +19,7 @@ import numpy as np
 from .wrapped_decorator import signature_safe_contextmanager
 from .core import VarDesc
 from . import unique_name
+from .imperative import base
 
 __all__ = [
     'Constant', 'Uniform', 'Normal', 'TruncatedNormal', 'Xavier', 'Bilinear',
@@ -165,7 +166,8 @@ class ConstantInitializer(Initializer):
                 'force_cpu': self._force_cpu or force_init_on_cpu()
             },
             stop_gradient=True)
-        var.op = op
+        if not base.enabled():
+            var.op = op
         return op
 
 
@@ -244,7 +246,8 @@ class UniformInitializer(Initializer):
                 attrs={"in_dtype": out_var.dtype,
                        "out_dtype": var.dtype})
 
-        var.op = op
+        if not base.enabled():
+            var.op = op
         return op
 
 
@@ -322,7 +325,8 @@ class NormalInitializer(Initializer):
                 outputs={"Out": var},
                 attrs={"in_dtype": out_var.dtype,
                        "out_dtype": var.dtype})
-        var.op = op
+        if not base.enabled():
+            var.op = op
         return op
 
 
@@ -400,7 +404,8 @@ class TruncatedNormalInitializer(Initializer):
                 outputs={"Out": var},
                 attrs={"in_dtype": out_var.dtype,
                        "out_dtype": var.dtype})
-        var.op = op
+        if not base.enabled():
+            var.op = op
         return op
 
 
@@ -505,7 +510,8 @@ class XavierInitializer(Initializer):
                     "seed": self._seed
                 },
                 stop_gradient=True)
-        var.op = op
+        if not base.enabled():
+            var.op = op
         return op
 
 
@@ -605,7 +611,8 @@ class MSRAInitializer(Initializer):
                     "seed": self._seed
                 },
                 stop_gradient=True)
-        var.op = op
+        if not base.enabled():
+            var.op = op
         return op
 
 
@@ -703,7 +710,8 @@ class BilinearInitializer(Initializer):
                 'shape': list(shape),
                 value_name: values
             })
-        var.op = op
+        if not base.enabled():
+            var.op = op
         return op
 
 
@@ -761,7 +769,8 @@ class NumpyArrayInitializer(Initializer):
                 value_name: values
             },
             stop_gradient=True)
-        var.op = op
+        if not base.enabled():
+            var.op = op
         return op