Some JavaVirtualMachine''''''s have the ability to run a thread scheduling system wrapped inside of a single system process. One benefit of green threads is low thread creation overhead.  A drawback is  java vm implementors probably aren't as good at thread scheduling as your OS, and possible ambiguity in scheduling policies (what scheduling policy did the VM implementor use?).

Contrast to NativeJavaThreads (aka "heavyweight threads"). 

-McClainLooney

A disadvantage of green Java threads is that JNI does not define an API for interacting with the thread scheduler, so native code that makes blocking system calls will allow other threads to run when the JVM uses native threads but will block the entire Java process when the JVM uses green threads.

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See GreenVsNativeThreads

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CategoryJava CategoryConcurrency