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62 lines
1.7 KiB
62 lines
1.7 KiB
11 years ago
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# Tracing
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Stability: 1 - Experimental
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The tracing module is designed for instrumenting your Node application. It is
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not meant for general purpose use.
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***Be very careful with callbacks used in conjunction with this module***
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Many of these callbacks interact directly with asynchronous subsystems in a
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synchronous fashion. That is to say, you may be in a callback where a call to
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`console.log()` could result in an infinite recursive loop. Also of note, many
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of these callbacks are in hot execution code paths. That is to say your
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callbacks are executed quite often in the normal operation of Node, so be wary
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of doing CPU bound or synchronous workloads in these functions. Consider a ring
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buffer and a timer to defer processing.
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`require('tracing')` to use this module.
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## v8
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The `v8` property is an [EventEmitter][], it exposes events and interfaces
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specific to the version of `v8` built with node. These interfaces are subject
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to change by upstream and are therefore not covered under the stability index.
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### Event: 'gc'
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`function (before, after) { }`
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Emitted each time a GC run is completed.
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`before` and `after` are objects with the following properties:
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```
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{
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type: 'mark-sweep-compact',
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flags: 0,
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timestamp: 905535650119053,
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total_heap_size: 6295040,
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total_heap_size_executable: 4194304,
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total_physical_size: 6295040,
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used_heap_size: 2855416,
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heap_size_limit: 1535115264
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}
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```
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### getHeapStatistics()
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Returns an object with the following properties
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```
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{
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total_heap_size: 7326976,
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total_heap_size_executable: 4194304,
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total_physical_size: 7326976,
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used_heap_size: 3476208,
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heap_size_limit: 1535115264
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}
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```
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[EventEmitter]: events.html#events_class_events_eventemitter
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