Does anyone use tcmalloc's debugging envvars?

[Nico Weber]

Hi,

tcmalloc contains a bunch of flags that are defined like

  DEFINE_int32(verbose, EnvToInt("PERFTOOLS_VERBOSE", 0), "Verbose description.");

where EnvToFoo is defined as

  #define EnvToInt(envname, dflt) \

    (!getenv(envname) ? (dflt) : strtol(getenv(envname), NULL, 10))

So ever one of these flags add a static initializer. My guess is that nobody ever uses any of tcmalloc's debug env vars, so I'd like to change EnvToFoo in tcmalloc/chromium to just always evaluate to `dftl`.

If you do use tcmalloc's debugging envvars, shout, then I'd make EnvToFoo use the env conditionally on some define and add a gyp define to set that define – then you can set that define for your things, but prod builds won't get these initializers.

Thanks,

Nico

[Dai Mikurube]

Deep Memory Profiler actually depends on some of these envvars: HEAPPROFILE, HEAP_PROFILE_TIME_INTERVAL, HEAP_PROFILE_MMAP and DEEP_HEAP_PROFILE... http://dev.chromium.org/developers/deep-memory-profiler

I guess some other profiling features may be using them.

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Dai MIKURUBE

   dmik...@chromium.org

[Nico Weber]

Does DMP set some preprocessor define?

[William Chan (陈智昌)]

I've used the environment variables before. Not the first one you mentioned, but some of the others that Dai did. Specifically, I use the ones for profiling, which gets enabled using the profiling gyp flag. So you might just use that gyp flag for the relevant environment variables.

[Dai Mikurube]

DMP depends on tcmalloc's heap-profiler which is started with the envvars (in third_party/tcmalloc/chromium/src/heap-profiler.cc and deep-heap-profile.cc).  DMP also depends on the 'profiling' gyp flag. So, yes, it'd be okay if it's turned on when 'profiling=1'.

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Dai MIKURUBE

   dmik...@chromium.org

[Nico Weber]

Cool! https://codereview.chromium.org/281613004/