[joyeecheung]

Probe mode currently only launches a new process from the entry point script. This change lets it attach to an already-running process, so a long-lived application can be inspected without restarting it.

Running node inspect --probe without specifying an entry point script instructs Node.js to attach to a running Node.js process and probe. The way attaching is done is specified through command line arguments:

• --pid <pid> activates the target's inspector (if it's not already activated) and connects to it.
• --host <host> and --port <port> specify an address where an inspector is listening. The host defaults to 127.0.0.1 and the port defaults to 9229.

When the session ends, probe mode resumes and detaches instead of killing a process it does not own. The report now includes a top-level target field describing what was probed, and each probe contains a locations field about where it bound.

An attach session ends when a probe reaches --max-hit (reported as completed), when the target finishes on its own (completed, or miss with the pending probes, and the target is then allowed to exit), or when --timeout fires (reported as timeout, the probing process exit with 0 and reports the hits recorded so far).

--timeout now is also applied to the startup phase in both modes, so a target that never responds before the breakpoints are bound is reported as an error instead of hanging.

# Probing a process by PID, which may not already have the inspector listening.
# End the probing session when the specified probe is reached 5 times.
$ node inspect --probe app.js:42 --expr "req.url" --max-hit 5 --pid 12345

# Probing a process that's already listening for inspector connections at 127.0.0.1:9229.
# End the probing session when the specified timeout is reached.
$ node inspect --probe app.js:42 --expr "req.url" --timeout 50000 --host 127.0.0.1 --port 9229

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/78792/

[codecov]

Codecov Report

❌ Patch coverage is 79.76540% with 69 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.71%. Comparing base (1d3835e) to head (c2881e9).
⚠️ Report is 68 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/internal/debugger/inspect_probe.js	76.84%	62 Missing and 4 partials ⚠️
lib/internal/debugger/inspect.js	62.50%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #67201      +/-   ##
==========================================
+ Coverage   90.65%   90.71%   +0.05%     
==========================================
  Files         797      797              
  Lines      278780   279168     +388     
  Branches    53611    53704      +93     
==========================================
+ Hits       252739   253242     +503     
+ Misses      16385    16291      -94     
+ Partials     9656     9635      -21     

Files with missing lines	Coverage Δ
lib/internal/debugger/inspect_client.js	88.04% <100.00%> (+0.09%)	⬆️
lib/internal/debugger/inspect_helpers.js	93.14% <100.00%> (+0.61%)	⬆️
lib/internal/debugger/inspect.js	93.29% <62.50%> (-0.71%)	⬇️
lib/internal/debugger/inspect_probe.js	83.76% <76.84%> (+0.79%)	⬆️

... and 61 files with indirect coverage changes

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[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/78815/