問題描述
Java API 線程優(yōu)先級 (1-10) 如何轉(zhuǎn)換為操作系統(tǒng)級別的優(yōu)先級，因?yàn)榇蠖鄶?shù)操作系統(tǒng)沒有與此匹配的線程優(yōu)先級(在數(shù)量方面).
How are the java API thread priorities (1-10) gets translated to the OS level priorities since most OS don't have thread priority levels (in terms of number) which match this.
因此請記住，是否存在兩個(gè)或多個(gè)具有不同優(yōu)先級的線程最終在操作系統(tǒng)級別獲得相同優(yōu)先級的情況.
So keeping in mind , can there be a scenario when two or more threads with different priorities eventually get the same priority at OS level.
請澄清，如果我的理解有一些更正.
Please clarify, if I there is some correction in my understanding.
推薦答案
確實(shí)，某些優(yōu)先級可以映射到相同的本機(jī)"優(yōu)先級.以下是列表(基于 OpenJDK 6 中的 Hotspot 代碼):
Indeed, some priority levels can map to the same "native" priority level. Here's the list (based on the Hotspot code in OpenJDK 6):
- 1 ? 0
- 2 ? 32
- 3 ? 64
- 4 ? 96
- 5 – 10 ? 127
值得注意的是，在 Solaris 上，您不能將線程優(yōu)先級提高到高于正常水平，只能降低它:5 的優(yōu)先級值與任何更高的值相同.
Of note is that on Solaris, you can't raise the thread priority above normal, only lower it: the priority value for 5 is the same as any of the higher values.
- 1 – 10 ? 4 – -5(
nice值)
值得注意的是，在 Linux 上，Java 中不同的線程優(yōu)先級確實(shí)映射到本機(jī)級別的不同優(yōu)先級值.
Of note is that on Linux, different thread priorities in Java do map to distinct priority values at native level.
- 1 – 2 ?
THREAD_PRIORITY_LOWEST - 3 – 4 ?
THREAD_PRIORITY_BELOW_NORMAL - 5 – 6 ?
THREAD_PRIORITY_NORMAL - 7 – 8 ?
THREAD_PRIORITY_ABOVE_NORMAL - 9 – 10 ?
THREAD_PRIORITY_HIGHEST
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