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[Inference] Fix mem release problem #32654

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merged 1 commit into from
Apr 29, 2021

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jiweibo
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@jiweibo jiweibo commented Apr 28, 2021

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Describe

目前Predictor释放的时候,发现有一瞬间会占用所有显卡的显存。

定位到该问题在于 Predictor内部的scope_在析构的时候会遍历所有的卡,依次调用memory::Release(place)接口,该接口需调用cuda底层函数,所以会申请cuda handle等,占用显存。

    scope_.reset(new paddle::framework::Scope(), [](framework::Scope *scope) {
      delete scope;
#if defined(PADDLE_WITH_CUDA) || defined(PADDLE_WITH_HIP)
      for (int dev_id = 0; dev_id < paddle::platform::GetCUDADeviceCount();
           ++dev_id) {
        memory::Release(platform::CUDAPlace(dev_id));
      }
#endif
#ifdef PADDLE_WITH_XPU
      for (int dev_id = 0; dev_id < paddle::platform::GetXPUDeviceCount();
           ++dev_id) {
        memory::Release(platform::XPUPlace(dev_id));
      }
#endif
      memory::Release(platform::CPUPlace());
    });

在Predictor Clone()接口调用后,Scope_的声明周期可能比Predictor要长,所以无法获取用户指定的显卡即device_id,该pr的修改会导致未定义的问题:https://github.com/PaddlePaddle/Paddle/pull/28409/files#diff-f6feda974e038d722114830a39bea985fd814e28bd86bcd33248aece3c3181a4R178

所以在此处,我们去除全部遍历显卡,依次释放的逻辑,恢复原有代码逻辑,这样会导致,权重所占据的显存最后会归还显存池,但不会压缩显存池的大小。

旧有问题现象:
测试代码:https://github.com/PaddlePaddle/Paddle-Inference-Demo/tree/master/c%2B%2B/test/shrink_memory
1、初始化Predictor后(config设置initGpu为500M),显存为780M(handle + 权重等)
2、batch_size为100运行一次,显存为4418M
3、调用ShrinkMemory接口后,显存占用为1292M(handle + 权重 + 其它?)
4、batch_size为2运行一次,显存占用为1728M
5、Predictor析构后,0卡显存占用为792M,其它卡占用280M

更改代码逻辑后,

5、Predictor析构后,显存占用1292M,但不影响其它卡显存占用。

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CLAassistant commented Apr 28, 2021

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All committers have signed the CLA.

@jiweibo jiweibo merged commit dec8ab8 into PaddlePaddle:develop Apr 29, 2021
@jiweibo jiweibo deleted the fix_mem_release branch April 29, 2021 02:01
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3 participants