How to enable tensorflow VLOG inside c++ core implementation

[Wangda Tan]

Hi everyone,

I'm learning tensorflow core implementation right now, I found inside c++ core implementation there're lots of verbose messages like:

    VLOG(1) << "Direct session inter op parallelism threads: " << num_threads;

However I found in implementation, it doesn't look like works:

    // TODO(jeff): Define a proper implementation of VLOG_IS_ON

    #define VLOG_IS_ON(lvl) ((lvl) <= 0)

    #define VLOG(lvl)      \

        if (VLOG_IS_ON(lvl)) \

          ::tensorflow::internal::LogMessage(__FILE__, __LINE__, tensorflow::INFO)

I'm not sure how to enable such debug logs while running a normal tensorflow script (like mnist.py), I think it will be pretty helpful for new developers to understand overall logic!

Thanks in advance!

Best,

Wangda Tan

[Yaroslav Bulatov]

Unfortunately you to rebuild from source in order to change that setting

IE, to enable verbose 1 logging, change that to

define VLOG_IS_ON(lvl) ((lvl) <= 1)

BTW, messages can come out of order because of threads/buffering, so another useful thing is to add timestamps to the logs, in tensorflow/core/platform/default/logging.cc

inline static double CurrentRealTimeMillis() {

 +    struct timespec tm;

 +    clock_gettime(CLOCK_MONOTONIC, &tm);

 +    return tm.tv_sec * 1000LL + double(tm.tv_nsec) / 1000000LL;

 +}

 +

  void LogMessage::GenerateLogMessage() {

    // TODO(jeff,sanjay): For open source version, replace this with something

    // that logs through the env or something and fill in appropriate time info.

 +

 +  fprintf(stderr, "%c %.6f file %s:%d] %s\n", "IWEF"[severity_], CurrentRealTimeMillis(), fname_, line_, str().c_str());

  }

If you are on Linux/CUDA 8, here's a wheel with both of these changes

https://www.dropbox.com/s/pyu92nj4oifw6cg/tensorflow-0.12.0rc0-cp35-cp35m-linux_x86_64.whl?dl=0

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[Wangda Tan]

Hi Yaroslav,

Really appreciate your response, very helpful!

Regards,

Wangda

[Wangda Tan]

Opened #6366.

Thanks,

[Mohamed Akrout]

Hi Yaroslav,

If I activate VLOG by compiling tensorflow from source, when can I find the log file generated ?

For instance, in the file tensor.cc we have:

if (LogMemory::IsEnabled()) {

    RecordDeallocation();

  }

and the isEnabled function is as follows:

bool LogMemory::IsEnabled() { return VLOG_IS_ON(1); }

How Can I activate the LogMemory logs and where these logs will be created ?

Thank you.

Mohamed

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[Bairen Yi]

FYI:

https://github.com/tensorflow/tensorflow/pull/6375

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