التثبيت (Pinning) ومزالق أخرى

في هذا الدرس

know when virtual threads do not help.

الموضوعات المخطط لها

• Pinning: a virtual thread cannot unmount while blocked, holding its carrier. Causes include blocking inside synchronized on older JDKs and native frames; newer JDKs reduce synchronized pinning (verify version).
• Diagnose with JFR's virtual thread pinned event or -Djdk.tracePinnedThreads (verify flags).
• CPU-bound work gains nothing; carriers equal about the number of cores.
• Downstream limits: 10,000 virtual threads can hit a 10-connection database pool, so the bottleneck moves.
• Use semaphores or pool limits to protect downstream resources.