CodyC•17mo ago

Help debugging command that doesn't exit.

Is there a way to have Deno tell me what async tasks are still pending when a program ends? I'm using a third-party API, and AFAICT awaiting all the promises I can, but I still get to the end of my main() and deno doesn't exit. So I've got:

async function main() {
    // [snip]
    console.log("Done")
    showPending()
}

function showPending() {
    let {ops} = Deno.metrics()
    for (let [key, value] of Object.entries(ops)) {
        if (value.opsDispatched != value.opsCompleted) {
            console.log(key, value)
        }
    }
    console.log(Deno.resources())
}

async function main() {
    // [snip]
    console.log("Done")
    showPending()
}

function showPending() {
    let {ops} = Deno.metrics()
    for (let [key, value] of Object.entries(ops)) {
        if (value.opsDispatched != value.opsCompleted) {
            console.log(key, value)
        }
    }
    console.log(Deno.resources())
}

Which gives me:

[snip]
Done
op_read {
  opsDispatched: 14,
  opsDispatchedSync: 0,
  opsDispatchedAsync: 14,
  opsDispatchedAsyncUnref: 0,
  opsCompleted: 13,
  opsCompletedSync: 0,
  opsCompletedAsync: 13,
  opsCompletedAsyncUnref: 0,
  bytesSentControl: 0,
  bytesSentData: 0,
  bytesReceived: 0
}
{
  "0": "stdin",
  "1": "stdout",
  "2": "stderr",
  "8": "childStdin",
  "9": "childStdout",
  "10": "child"
}

[snip]
Done
op_read {
  opsDispatched: 14,
  opsDispatchedSync: 0,
  opsDispatchedAsync: 14,
  opsDispatchedAsyncUnref: 0,
  opsCompleted: 13,
  opsCompletedSync: 0,
  opsCompletedAsync: 13,
  opsCompletedAsyncUnref: 0,
  bytesSentControl: 0,
  bytesSentData: 0,
  bytesReceived: 0
}
{
  "0": "stdin",
  "1": "stdout",
  "2": "stderr",
  "8": "childStdin",
  "9": "childStdout",
  "10": "child"
}

Any suggestions? I guess I'll fire up a debugger...

2 Replies

CodyC•17mo ago

Well, since deno test --trace-ops does what I want, I just wrapped my call in a test and ran it that way. Looks like esbuild isn't cleaning up after itself:

 - 1 async operation to op_read was started in this test, but never completed. The operation was started here:
    at handleOpCallTracing (ext:core/01_core.js:216:42)
    at opAsync (ext:core/01_core.js:209:15)
    at read (ext:deno_io/12_io.js:108:28)
    at FsFile.read (ext:deno_fs/30_fs.js:609:12)
    at readMoreStdout (https://deno.land/x/esbuild@v0.17.12/mod.js:1894:49)
    at https://deno.land/x/esbuild@v0.17.12/mod.js:1899:11

 - 1 async operation to op_read was started in this test, but never completed. The operation was started here:
    at handleOpCallTracing (ext:core/01_core.js:216:42)
    at opAsync (ext:core/01_core.js:209:15)
    at read (ext:deno_io/12_io.js:108:28)
    at FsFile.read (ext:deno_fs/30_fs.js:609:12)
    at readMoreStdout (https://deno.land/x/esbuild@v0.17.12/mod.js:1894:49)
    at https://deno.land/x/esbuild@v0.17.12/mod.js:1899:11

CodyC•17mo ago

There's an undocumented stop() method that you have to call to avoid this problem. 🤦 https://deno.land/x/esbuild@v0.17.12/mod.js?s=stop This doesn't seem to be documented in the official API docs: https://esbuild.github.io/api/

esbuild - API