Oracle International Corporation

Ron Pressler

Erik Duveblad

Erik Österlund

Techniques for lazy copying of runtime-managed stack frames are disclosed. A runtime environment generates a runtime-managed stack including multiple frames. A topmost subset of frames includes data associated with particular instructions and a return address. A lower subset of frames includes data associated with different instructions. The runtime environment stores a copy of the topmost subset of frames in an OS-managed stack, without copying the lower subset. The particular instructions execute using the copy of the topmost subset of frames in the OS-managed stack. The runtime environment replaces, in the copy, the return address with a return barrier address. When execution of the instructions terminates, control passes to return barrier instructions, which store a copy of the lower subset of frames in the OS-managed stack and pass control to the different instructions. The different instructions execute using the copy of the lower subset of frames in the OS-managed stack.

Lazy copying of runtime-managed stack frames

Techniques for efficient continuation stack storage are disclosed. In some embodiments, when a continuation yields, the continuation stack, or portion thereof, is copied from a thread stack to a data object, referred to herein as a chunk, allocated from memory. The copied stack portion may maintain the same representation in the chunk as on the thread stack to minimize processing overhead of the operation. When the continuation resumes, the continuation stack, or some portion thereof, is copied from the chunk to the thread stack. During execution, the continuation stack that was copied may be modified on the thread stack. When the continuation yields again, the runtime environment may determine, based at least in part on whether the first object in memory is subject to a garbage collection barrier, whether to copy the modified portion of the continuation stack to the existing chunk or to allocate a new chunk.

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London, United Kingdom

Ron Pressler