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cluster: make --prof work for workers

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Profiling in clustered environments doesn't work out of the box.

By default, V8 writes the profile data of all processes to a single
v8.log.

Running that log file through a tick processor produces bogus numbers
because many events won't match up with the recorded memory mappings
and you end up with graphs where 80+% of ticks is unaccounted for.

Fixing the tick processor to deal with multi-process output is not very
useful because the processes may be running wildly disparate workloads.

That's why we fix up the command line arguments to include
a "--logfile=v8-%p.log" argument (where %p is expanded to the PID)
unless it already contains a --logfile argument.

Fixes #4617.
This commit is contained in:
Ben Noordhuis 2013-01-18 12:44:10 +01:00
parent 8b0f3ce397
commit 6b713b5253
1 changed files with 22 additions and 1 deletions
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23
lib/cluster.js
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@ -105,10 +105,31 @@ cluster.setupMaster = function(options) {
// Get filename and arguments
options = options || {};
// By default, V8 writes the profile data of all processes to a single
// v8.log.
//
// Running that log file through a tick processor produces bogus numbers
// because many events won't match up with the recorded memory mappings
// and you end up with graphs where 80+% of ticks is unaccounted for.
//
// Fixing the tick processor to deal with multi-process output is not very
// useful because the processes may be running wildly disparate workloads.
//
// That's why we fix up the command line arguments to include
// a "--logfile=v8-%p.log" argument (where %p is expanded to the PID)
// unless it already contains a --logfile argument.
var execArgv = options.execArgv || process.execArgv;
if (execArgv.some(function(s) { return /^--prof/.test(s); }) &&
!execArgv.some(function(s) { return /^--logfile=/.test(s); }))
{
execArgv = execArgv.slice();
execArgv.push('--logfile=v8-%p.log');
}
// Set settings object
settings = cluster.settings = {
exec: options.exec || process.argv[1],
execArgv: options.execArgv || process.execArgv,
execArgv: execArgv,
args: options.args || process.argv.slice(2),
silent: options.silent || false
};