[GitHub] [incubator-mxnet] yuxihu edited a comment on issue #13951: Gluon RNN memory leaks with extra variables

[GitBox <gi...@apache.org>]

yuxihu edited a comment on issue #13951: Gluon RNN memory leaks with extra variables
URL: https://github.com/apache/incubator-mxnet/issues/13951#issuecomment-470653186
 
 
   The memory leak is related to the extra unused variable you passed into your RNN model but it is NOT specific to RNN. In your repro script, you created a size-zero ndarray in each loop which caused the memory leak.
   ```
   for epoch in range(args.epochs):
       ...
       for i, (data, target) in enumerate(train_data):
           ...
           with autograd.record():
               ....
               output, hidden = model(data, hidden, mx.nd.array([], ctx=context))
   ```
   However, since the size-zero ndarray is unused anywhere, it is a better code practice to create once outside the loop and use it throughout your training. The same change applies to the eval() function in your repro script.
   ```
   extra = mx.nd.array([], ctx=context)
   for epoch in range(args.epochs):
       ...
       for i, (data, target) in enumerate(train_data):
           ...
           with autograd.record():
               ....
               output, hidden = model(data, hidden, extra)
   ```
   With this change, I ran your repro script for 10 epochs with mxnet_cu90mkl 1.3.1 and 1.4.0 packages and did not see memory leak.
   
   But there is indeed a memory leak issue which is the root cause for this issue. Please refer to #14358 for more details.

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