Bug or Feature: directly assign 'true' to `delay_alloc` of `Chunk` rather than using input param `delay_alloc_`?

[ooooona]

Description

I'm confuse about the coding here:

/*! \brief construct a new chunk */    
Chunk(mxnet::TShape shape, Context ctx_, bool delay_alloc_, int dtype)       
 : static_data(false), delay_alloc(true), ctx(ctx_),          
    storage_ref_(Storage::_GetSharedRef()),          
    engine_ref_(Engine::_GetSharedRef()) {      
  storage_shape = shape;      
  if (shape_is_known(storage_shape)) {        
    shandle.size = shape.Size() * mshadow::mshadow_sizeof(dtype);      
  } 
   var = Engine::Get()->NewVariable(); 
   shandle.ctx = ctx_; 
   if (!delay_alloc_) { 
     this->CheckAndAlloc(); 
   }
  }

here is source code

question

why not assign delay_alloc_ to delay_alloc?

[szha]

Nice catch. Looks like a bug to me. @ooooona thanks for reporting. Would you like to open a pull request and fix the bug?

[szha]

Seems to be introduced by #14223

[ooooona]

Nice catch. Looks like a bug to me. @ooooona thanks for reporting. Would you like to open a pull request and fix the bug?

sure, i will try it later today :)

[wkcn]

Thank you for pointing it out : )

It is a confusing variable name, but it is not a bug.

The meanings of decay_alloc_ and decay_alloc are different.
The former decay_alloc_ is an argument to decide whether the chunk need to decay-allocated.
But the later decay_alloc is the state whether the memory has not been allocated.

For the two cases decay_alloc_ is true or false,

• When the argument decay_alloc_ is true,

  1. decay_alloc = true;
  2. the condition if (!delay_alloc_) does not be satisfied.

• When the argument decay_alloc_ is false, the following steps will be executed:

  1. decay_alloc = true;
  2. The condition if (!decay_alloc_) is satisfied, then the function CheckAndAlloc() be called.
  3. Allocate the memory for the chunk, then decay_alloc is set as false.
     https://github.com/apache/incubator-mxnet/blob/b54b7f36c944b933f2aa94f224821548da5fcaf6/include/mxnet/ndarray.h#L1018-L1026

CheckAndAlloc() will allocate memory when decay_alloc is true.

Therefore, decay_alloc should be initialized as true whenever decay_alloc_ is true or false.