batch-cluster

batch-cluster

Support external batch-mode tools within Node.js

Many command line tools, like ExifTool and GraphicsMagick, support running arbitrary commands via a "batch mode," which amortizes process spin-up costs over several, serial request/response pairs, sent via stdin/stdout.

Spinning up N of these child processes on multiprocessor machines gives you parallelism.

Distributing requests to these processes, monitoring and restarting processes as needed, and shutting them down appropriately, is what this module gives you.

This package powers exiftool-vendored.

Changelog

v1.1.0

• ✨ BatchCluster now has a force-shutdown exit handler to accompany the graceful-shutdown beforeExit handler. For reference, from the Node docs:

The 'beforeExit' event is not emitted for conditions causing explicit termination, such as calling process.exit() or uncaught exceptions.

• ✨ Remove Rate's time decay in the interests of simplicity

v1.0.0

• ✨ Integration tests now throw deterministically random errors to simulate flaky child procs, and ensure retries and disaster recovery work as expected.
• ✨ If the processFactory or versionCommand fails more often than a given rate, BatchCluster will shut down and raise exceptions to subsequent enqueueTask callers, rather than try forever to spin up processes that are most likely misconfigured.
• ✨ Given the proliferation of construction options, those options are now sanity-checked at construction time, and an error will be raised whose message contains all incorrect option values.

v0.0.2

• ✨ Added support and explicit tests for CR LF, CR, and LF encoded streams from exec'ed processes
• ✨ child processes are ended after maxProcAgeMillis, and restarted as needed
• 🐞 BatchCluster now practices good listener hygene for process.beforeExit

v0.0.1

• ✨ Extracted implementation and tests from exiftool-vendored

Versioning

The MAJOR or API version is incremented for

• 💔 Non-backwards-compatible API changes

The MINOR or UPDATE version is incremented for

• ✨ Backwards-compatible features

The PATCH version is incremented for

• 🐞 Backwards-compatible bug fixes
• 📦 Minor packaging changes

Changelog

v1.1.0

• ✨ BatchCluster now has a force-shutdown exit handler to accompany the graceful-shutdown beforeExit handler. For reference, from the Node docs:

The 'beforeExit' event is not emitted for conditions causing explicit termination, such as calling process.exit() or uncaught exceptions.

• ✨ Remove Rate's time decay in the interests of simplicity