Garbage collection safepoint system using non-blocking asynchronous I/O call to copy data when the garbage collection safepoint is not in progress or is completed

摘要

A system and method for providing direct socket input/output (I/O) for Java in a Java Virtual Machine (JVM) environment. During runtime, the system periodically garbage collects software objects in the Java memory space or heap. In accordance with an embodiment, the system provides a means to change the state of a thread performing the I/O which temporarily disallows garbage collection from taking place, thus guaranteeing that a receiving object in the heap does not move. The use of safepoints to prohibit GC from happening during the I/O call means that a global GC lock is not required. Non-blocking I/O is utilized, while prohibiting a thread from entering a GC safepoint during an I/O system call. The technique addresses disadvantages of previous methods by removing contended locks and by removing restrictions on allocation. In accordance with an embodiment, a special thread state can be used to prevent the thread from entering a GC safepoint.