The default V8 platform uses Memory Protection Keys (pkeys) which
require all V8-using threads to be descendants of the thread that
called v8::Initialize. Tokio's spawn_blocking pool threads don't
satisfy this, causing SIGSEGV in WasmCodePointerTable during isolate
creation on x86_64 Linux.
Switch to new_unprotected_default_platform which relaxes the pkey
requirement. Also remove --single-threaded V8 flag (was degrading
performance without fixing the issue) and scope the creation mutex
to just JsRuntime::new() instead of the entire lifecycle.
See: https://github.com/denoland/deno_core/issues/952
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
90d010347c