yorickhardy 71e5aa2dd6 Improve garbage collection for terminated threads (#550) ... * gc: add a function to force the collector to run This requires adding a "forced" stage for the collector, which is the initial stage for a forced collection. Thereafter, the collector continues to the usual stages of collection. * runtime: force the garbage collector to run when a thread exits This is a first attempt to improve the memory usage reported in issue #534. * srfi-18: call Cyc_end_thread on thread exits This ensures that the collector has a chance to run whenever a thread exits. Attempts to partially address issue #534. * gc: free unused parts of the heap before merging When a thread exits, the heap is merged into the main thread. Before doing so, free any unused parts of the heap to reduce memory usage. Attempts to partially address issue #534. * srfi-18: thread-terminate! takes a thread as argument * gc: revert adding STAGE_FORCING Use gc_start_major_collection() instead. Partial work towards addressing issue #534. * gc: free empty pages in gc_heap_merge() Moving the code from gc_merge_all_heaps to gc_heap_merge removes special handling of the start of the list and is (hopefully) easier to read. Partial work towards addressing issue #534. * gc: oops, forgot the "freed" count Partial work towards addressing issue #534. * gc: oops, forgot the "freed" count (again) Partial work towards addressing issue #534. * types: update forward declaration of gc_heap_merge() Partial work towards addressing issue #534. * gc: remove accidental double counting * runtime: small (cosmetic) simplification * srfi-18: add a slot for thread context in the thread object Partial work towards addressing issue #534. * srfi-18: do a minor gc when terminating a thread This ensures that any objects which are part of the thread context are transferred to the heap. Partial work towards addressing issue #534. * types.h: make gc_alloc_pair public This will be used to create the thread context. Partial work towards addressing issue #534. * gc: prepare heap objects for sweeping Also introduce a global variable to track whether merged heaps need to be swept. Partial work towards addressing issue #534. * gc: create a context for terminated thread objects The context ensures that parametrised objects, continuations and exception handlers can still be traced but are no longer root objects (after thread terminations) and can be GCd eventually. Partial work towards addressing issue #534. * gc: sweep and free empty heaps for the primordial thread The primordial thread may not have an opportunity to sweep heap pages which have been merged from terminated threads. So sweep any unswept pages during the cooperation phase. Partial work towards addressing issue #534. * srfi-18: revert thread-terminate! changes These changes need to be revisited, and are not suitable for the threads garbage collection pull request.		2025-01-20 21:10:49 -05:00
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cyclone	Improve garbage collection for terminated threads (#550)	2025-01-20 21:10:49 -05:00