@contrast/heapdump v1.1.0
node-heapdump
Make a dump of the V8 heap for later inspection.
Install
npm install @contrast/heapdump
Build
node-gyp rebuild
Usage
Load the add-on in your application:
var heapdump = require('@contrast/heapdump');
The module exports a single writeSnapshot([filename])
function that will write a heapdump to disk.
heapdump.writeSnapshot('/var/local/' + Date.now() + '.heapsnapshot');
The snapshot is written synchronously to disk. When the JS heap is large, it may introduce a noticeable "hitch".
Inspecting the snapshot
Open Google Chrome and press F12 to open the developer toolbar.
Go to the Memory
tab, right-click in the tab pane and select
Load profile...
.
Select the dump file and click Open
. You can now inspect the heap snapshot
at your leisure. Some snapshots may take a long time to load, on the order of
minutes or even hours.
Note that Chrome will refuse to load the file unless it has the .heapsnapshot
extension.
Caveats
On UNIX systems, the rule of thumb for creating a heap snapshot is that it
requires memory twice the size of the heap at the time of the snapshot.
If you end up with empty or truncated snapshot files, check the output of
dmesg
; you may have had a run-in with the system's OOM killer or a resource
limit enforcing policy, like ulimit -u
(max user processes) or ulimit -v
(max virtual memory size).