Linux JVM是否实际实现线程优先级？

好吧，让我们看一下源代码：

2947行：

////////////////////////////////////////////////////////////////////////////////// thread priority support// Note: Normal Linux applications are run with SCHED_OTHER policy. SCHED_OTHER// only supports dynamic priority, static priority must be zero. For real-time// applications, Linux supports SCHED_RR which allows static priority (1-99).// However, for large multi-threaded applications, SCHED_RR is not only slower// than SCHED_OTHER, but also very unstable (my volano tests hang hard 4 out// of 5 runs - Sep 2005).//// The following pre actually changes the niceness of kernel-thread/LWP. It// has an assumption that setpriority() only modifies one kernel-thread/LWP,// not the entire user process, and user level threads are 1:1 mapped to kernel// threads. It has always been the case, but could change in the future. For// this reason, the pre should not be used as default (ThreadPriorityPolicy=0).// It is only used when ThreadPriorityPolicy=1 and requires root privilege.

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第2982行：

 static int prio_init() {   if (ThreadPriorityPolicy == 1) {     // only root can raise thread priority. Don't allow ThreadPriorityPolicy=1     // if effective uid is not root. Perhaps, a more elegant way of doing     // this is to test CAP_SYS_NICE capability, but that will require libcap.so     if (geteuid() != 0) {       if (!FLAG_IS_DEFAULT(ThreadPriorityPolicy)) {         warning("-XX:ThreadPriorityPolicy requires root privilege on Linux");       }       ThreadPriorityPolicy = 0;     }   }   return 0; }

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第2997行：

OSReturn os::set_native_priority(Thread* thread, int newpri) {  if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) return OS_OK;  int ret = setpriority(PRIO_PROCESS, thread->osthread()->thread_id(), newpri);  return (ret == 0) ? OS_OK : OS_ERR;}

所以！至少在Sun
Java和Linux上，除非您已经完成

-XX:ThreadPriorityPolicy