heapdump-analyser v1.4.0
heapdump-analyser
heapdump-analyser dump.heapsnapshot
Enters interactive mode.
heapdump-analyser dump.heapsnapshot ClassToFind
heapdump-analyser dump.heapsnapshot ClosureToFind()
heapdump-analyser dump.heapsnapshot @IdToFind
Finds all ClassToFind
classes or ClosureToFind closures in the heapsnapshot and prints out a colorful retainer trace for them.
Compared to the v8 devtools it
- correctly analyses WeakMaps and circular dependencies within them.
- eliminates references between the classes/closures you are looking for.
Note that it may take a large amount of memory for the analysis so you may want to increase the max memory with NODE_OPTIONS=--max_old_space_size=16000
. It takes about 16x size of heapsnapshot.
Creating a heapsnapshot
Note that creating a heapsnapshot is pretty slow and blocks execution of your code.
Node.js CLI
Since Node.js 16 you can use --heapsnapshot-near-heap-limit=1
to create a heapsnapshot when the process runs out of memory. Best reduce the available amount of memory via --max_old_space_size=500
to make it run out of memory faster and make the size of the heapsnapshot smaller.
node --max_old_space_size=500 --heapsnapshot-near-heap-limit=1 program.js
It also possible to create a heapsnapshot on a signal via --heapsnapshot-signal=SIGUSR2
node --heapsnapshot-signal=SIGUSR2 program.js
ps aux
kill -USR2 1234
heapdump package
The npm package heapdump
allows to create a heapsnapshot from javascript:
console.log("creating heapdump...");
require("heapdump").writeSnapshot((err) => console.log("done", err));
Node.js devtools
Using the devtools is not recommended since the devtools affect the results, are very slow and crash when the heapsnapshot is too large.