Workers affected by V8 aborting on virtual allocation failure

* **Version**: 4b6e4c1eb110 * **Platform**: Linux 4.19.15 x86_64 * **Subsystem**: `worker_threads` A process aborts when V8 fails to allocate virtual memory. This is detremental to using `Workers` because: 1. If a `Worker` fails to allocate virtual memory during initialization the process aborts. 2. V8's virtual memory allocator doesn't play nicely with `ulimit`. To demonstrate this issue: 1. Set `ulimit -v` to some value smaller than actual physically available memory (I've allocated 8GB out of 16GB). 2. Run the following script that spawns a set number of `Worker`s (the number to spawn may need adjusting depending on the system): ```js const WORKER_COUNT = 60; // Value may need adjustment const { Worker, parentPort, workerData, threadId } = require('worker_threads'); const worker_array = []; if (workerData) { process._rawDebug(workerData, threadId, process.pid, process.ppid); parentPort.postMessage(42); setTimeout(() => {}, 1000000); return; } (function runner(n) { if (++n > WORKER_COUNT) return setTimeout(killAll, 10); const w = new Worker(__filename, { workerData: n }); w.on('message', () => { process._rawDebug(JSON.stringify(getMemUsage())); runner(n); }); w.on('exit', c => process._rawDebug(`${n} exited with ${c}`)); worker_array.push(w); })(0); function killAll() { for (let w of worker_array) w.terminate(); } function getMemUsage() { const o = process.memoryUsage(); for (let i in o) o[i] = o[i] / 1024; return o; } ``` Which results in a `Fatal process OOM in CodeRange setup: allocate virtual memory` error. With the stack trace of: ``` * thread #1: tid = 4094, 0x0000000003eab702 node_g`v8::base::OS::Abort() at platform-posix.cc:399, name = 'node_g', stop reason = signal SIGILL: illegal instruction operand * frame #0: 0x0000000003eab702 node_g`v8::base::OS::Abort() at platform-posix.cc:399 frame #1: 0x0000000002954ac2 node_g`v8::Utils::ReportOOMFailure(isolate=0x0000000005c13170, location="CodeRange setup: allocate…