summarize-sync-io

A tool for easier analysis of Node.js synchronous IO tracebacks.

Node's --trace-sync-io flag makes it output tracebacks to stderr when synchronous IO occurs.

However, the traceback spam isn't that easy to read, so that's where this tool comes in.

Usage

$ node --trace-sync-io slow_script.js 2>trace.txt
$ node summarize-sync-io.js < trace.txt

Command line parameters

Excluded stacks

By default, writes, requires and closes are filtered out.

To not filter them, use the --writes/--module-loads/--closes parameters, respectively.

You can also use --all to exclude all of those filters from being used.

Module matching

Add --match=my-module to filter the result to stacks that have at least one entry from a module whose path contains my-module.

Unsimplified paths

By default, module paths in the output only contain the bit after the last node_modules.

Pass --simplify-paths=false to disable this.