4 ms·

And TLABs causes more memory fragmentations and which lead to more GCs and more need for memory compaction. So finally Java solved the problem it created itself

• pcwalton 9y ago
  What? TLABs allow a bump allocator with copying collection, which results in the least kind of fragmentation you can possibly have—zero! How can TLABs increase fragmentation?
  • geodel 9y ago
    You can read at: https://www.thinkmind.org/download.php?articleid=icons_2012_8_10_20033 https://www.thinkmind.org/download.php?articleid=icons_2012_.... "Thread-local allocation buffers (TLABs) are widely used in memory allocators of garbage-collected systems to speed up the fast-path (thread-local allocation) and reduce global heap contention yet at the expense of increased memory fragmentation. Larger TLABs generally improve performance and scalability but only up to the point where more frequent garbage collection triggered by increased memory fragmen- tation begins dominating the overall memory management overhead. Smaller TLABs decrease memory fragmentation but increase the frequency of executing the slow-path (global allocation) and thus may reduce performance and scalability..."
    • pcwalton 9y ago
      That isn't relevant to what we're discussing here. The problem of fragmentation across arenas that that paper describes is a problem with any system that uses thread-local caching, including Go's tcmalloc. The type of fragmentation we're discussing is fragmentation within a memory arena. That is the kind of fragmentation that only a copying/compacting collector can eliminate.