block-trace's Introduction

block-trace

Figure out if your node process is blocked because the CPU is spinning and exit the program with a stack trace if that is the case.

Useful for debugging unresponsive servers.

npm install -g block-trace

Usage

Giving the following example program

console.log('Waiting 1s ...')

setTimeout(function () {
  console.log('Spinning the CPU now!')
  while (1) {}
}, 1000)

If you run this with block-trace by doing the following

block-trace node example.js

After 1s the program will exit with the following output

Waiting 1s ...
Spinning the CPU now!
Error: CPU is blocked
    at /Users/maf/dev/node_modules/block-trace/example.js:5:10
    at Timer.listOnTimeout (timers.js:92:15)

License

MIT

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block-trace's Issues

Customise the timeout

How would I go about customising the timeout? I'm not sure if I should alter https://github.com/mafintosh/block-trace/blob/master/bin.js#L33 or https://github.com/mafintosh/block-trace/blob/master/bin.js#L53 or both?

It would be great to be able to set BLOCK_TRACE_TIMEOUT as an environment variable and have it read from defaulting to 1000 if it wasn't set?

var timeoutEnv = Number(process.env.BLOCK_TRACE_TIMEOUT),
    timeout = Number.isNaN(timeoutEnv) ? 1000 : timeoutEnv;

I keep getting `unrefdHandle`

I added block-trace to my setup, and I'm frequently seeing:

Error: CPU is blocked
app_1       |     at Timer.unrefdHandle (timers.js:453:22)

This makes it a little hard to debug. Do you have any ideas why I might be unfredHandle and how to improve the situation to expose the actual function/line that is erroring (as per the README.md)?

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