Debugging — Elide Docs

Read errors

elide --error-format=plain run app.js

Plain errors go to stderr with a short stack; program output stays on stdout. Add --verbose or --debug for Elide’s own logs.

Viewing an uncaught program error in Elide

Flag	Effect
`--abort-on-uncaught-exception`	Print the error, then raise `SIGABRT` (exit `134`) so the OS writes a core dump.
`--redirect-warnings=FILE`	Write process warnings, such as `process.emitWarning()`, to `FILE`, not stderr.
`--timeout=DURATION`	Stop the program after `DURATION` (for example `30s`) with exit `124`.
`--max-mem=SIZE`	Limit the heap size, for example `512m`. Exceeding it fails with a nonzero exit.

elide --profiler and --debugger — profiler report and debug endpoints

Attach a debugger

Program	Flag	Listens on	Client
JavaScript, TypeScript, Python	`--debugger=cdp`	`ws://127.0.0.1:1337/…`	Chrome DevTools or any CDP client
JavaScript, TypeScript, Python	`--debugger=dap`	`127.0.0.1:4711`, waits for a client	Any DAP-capable editor
Java, Kotlin	`--debugger`	`127.0.0.1:5005` (JDWP), suspended	IntelliJ IDEA, VS Code, `jdb`

elide run --debugger=cdp app.js

Debugger listening on ws://127.0.0.1:1337/<id>/inspect
For help, see: https://docs.elide.dev/guides/debugging
E.g. in Chrome open: devtools://devtools/bundled/js_app.html?ws=127.0.0.1:1337/<id>/inspect

Open the devtools:// link in Chrome.

elide run --debugger=dap app.js
elide run --debugger Hello.kt

Listening for transport dt_socket at address: 5005

Change a listener’s address with --debugger-host and --debugger-port:

elide run --debugger=dap --debugger-port=5678 app.js
elide run --debugger=0.0.0.0:5005 Hello.kt

A number or host:port after --debugger is a JDWP address and applies to Java and Kotlin only. JDWP has no authentication: bind beyond loopback only on a trusted network, or use an SSH tunnel.

Debug tests

elide test --debugger
elide test --debugger=dap sample.test.mts
elide test --debugger=5005

Flag	Debugs
`--debugger`	Guest tests over CDP and JVM tests over JDWP on `5005`
`--debugger=cdp` or `dap`	Guest tests only
`--debugger=PORT`	JVM tests only

A path narrows guest tests to one file. Narrow JVM tests by package name, not by path. While a debugger is attached, guest test files run one at a time.

Measure coverage

elide run --coverage app.js

Elide prints a Coverage Report after the program exits, with statements, lines and functions covered per file.

Profile CPU time

elide run --profiler=cputracing app.js

╭Profiler Report───────────────────────────────────────────────────────────────╮
│ Location           Root               Total        Interpreted      Compiled │
│   app.js            fib       21.89k 100.0%      21.89k 100.0%        0 0.0% │
│   app.js       :program              1 0.0%           1 100.0%        0 0.0% │
╰──────────────────────────────────────────────────────────────────────────────╯

Total counts calls to each function. For JFR recordings, heap dumps and Linux perf, see Monitoring and Profiling.

Trace with Insights

// insight.js
insight.on("enter", (ctx) => {
  console.log("enter", ctx.name);
}, { roots: true });

elide run --insights=insight.js app.js

Each function entry prints a line such as enter fib. See the Insights API for events and filters.

Report a bug

elide info
elide agent diagnostics
elide agent bug

elide agent bug prints the issue tracker URL and a Markdown report template. Fill in the exact command, the expected behavior, and any crash report.