V8 Garbage Collection Log Parser

A simple tool for parsing V8 garbage collection logs.

Support

$3

At the moment only logs produced by --trace_gc, --trace_gc_nvp and --trace_gc_verbose are supported.

$3

The V8 versions used by Node.js LTS versions are supported. That is:

* Node v8.x: V8 v5.8.x (will be updated to v6.x soon)
* Node v6.x: V8 v5.1.281.x
* Node v4.x: V8 v4.5.103.x

We will drop support when the corresponding Node.js LTS version is dropped.

For the grammar of these logs, see grammar.md.

As CLI tool

``console
npm install -g v8-gc-log-parser


output the result as JSON to stdout


v8-gc-log-parse
`

API

$3

`js
const Parser = require('v8-gc-log-parser');
const parser = new Parser();
`

$3

First, create a parser instance

`js
const Parser = require('v8-gc-log-parser');
const parser = new Parser();
`
Then parse the log:

`js
// notice the new line character at the end of the log
const simple_log = '[43417:0x102004600] 9709 ms: Scavenge 344.4 (379.7) -> 342.8 (387.7) MB, 6.6 / 0.0 ms [allocation failure].\n'
parser.parseAllToData(simple_log);
`

The result will be:

`js
[{
pid: 43417,
isolate: '0x102004600',
time_since_init: 9709,
data: {
collector: 'scavenge',
start_object_size: 344.4,
end_object_size: 342.8,
start_memory_size: 379.7,
end_memory_size: 387.7,
pause: 6.6,
external_time: 0,
gc_reason: 'allocation failure'
},
type: 'trace'
}]
`

For logs produced by --trace_gc_nvp:

`js
const nvp_log = '[51548:0x102004600] 3912 ms: pause=2.4 mutator=383.5 gc=s reduce_memory=0 scavenge=2.18 old_new=0.12 weak=0.00 roots=0.05 code=0.00 semispace=1.97 object_groups=0.00 external_prologue=0.00 external_epilogue=0.00 external_weak_global_handles=0.01 steps_count=0 steps_took=0.0 scavenge_throughput=1073741824 total_size_before=52688696 total_size_after=52177656 holes_size_before=106616 holes_size_after=152344 allocated=16910984 promoted=1642176 semi_space_copied=1855136 nodes_died_in_new=20 nodes_copied_in_new=1 nodes_promoted=0 promotion_ratio=40.2% average_survival_ratio=70.3% promotion_rate=99.6% semi_space_copy_rate=45.4% new_space_allocation_throughput=3480.1 context_disposal_rate=0.0\n'

parser.parseAllToData(nvp_log);
`

Result:

`js
{
"pid": 51548,
"isolate": "0x102004600",
"time_since_init": 3912,
"data": {
"pause": 2.4,
"mutator": 383.5,
"gc": "s",
"reduce_memory": 0,
"scavenge": 2.18,
"old_new": 0.12,
"weak": 0,
"roots": 0.05,
"code": 0,
"semispace": 1.97,
"object_groups": 0,
"external_prologue": 0,
"external_epilogue": 0,
"external_weak_global_handles": 0.01,
"steps_count": 0,
"steps_took": 0,
"scavenge_throughput": 1073741824,
"total_size_before": 52688696,
"total_size_after": 52177656,
"holes_size_before": 106616,
"holes_size_after": 152344,
"allocated": 16910984,
"promoted": 1642176,
"semi_space_copied": 1855136,
"nodes_died_in_new": 20,
"nodes_copied_in_new": 1,
"nodes_promoted": 0,
"promotion_ratio": 40.2,
"average_survival_ratio": 70.3,
"promotion_rate": 99.6,
"semi_space_copy_rate": 45.4,
"new_space_allocation_throughput": 3480.1,
"context_disposal_rate": 0
},
"type": "nvp"
}
`

For logs produced by --trace_gc --trace_gc_verbose

`js
const verbose_log = [43748:0x103000000] Memory allocator, used: 7204 KB, available: 1459164 KB
[43748:0x103000000] New space, used: 957 KB, available: 50 KB, committed: 2048 KB
[43748:0x103000000] Old space, used: 888 KB, available: 0 KB, committed: 980 KB
[43748:0x103000000] Code space, used: 242 KB, available: 0 KB, committed: 1024 KB
[43748:0x103000000] Map space, used: 49 KB, available: 0 KB, committed: 80 KB
[43748:0x103000000] Large object space, used: 0 KB, available: 1458123 KB, committed: 0 KB
[43748:0x103000000] All spaces, used: 2137 KB, available: 1458173 KB, committed: 4132 KB
[43748:0x103000000] External memory reported: 0 KB
[43748:0x103000000] Total time spent in GC : 0.6 ms\n
parser.parseAllToData(verbose_log);
`

Result:

`js
{
"pid": 43748,
"isolate": "0x103000000",
"type": "verbose",
"data": {
"memory_allocator": {
"used": 7204,
"available": 1459164
},
"new_space": {
"used": 957,
"available": 50,
"committed": 2048
},
"old_space": {
"used": 888,
"available": 0,
"committed": 980
},
"code_space": {
"used": 242,
"available": 0,
"committed": 1024
},
"map_space": {
"used": 49,
"available": 0,
"committed": 80
},
"large_object_space": {
"used": 0,
"available": 1458123,
"committed": 0
},
"all_spaces": {
"used": 2137,
"available": 1458173,
"committed": 4132
},
"external_memory_reported": 0,
"total_time_spent_in_gc": 0.6
}
}
``

LICENSE

The MIT License (MIT)
Copyright (c) 2016 Alibaba Group