Thread Sharing Limits in Perl 5.10+
19K reputation · 01 Mar 2022, 02:37 UTC
Thread Sharing Limits in Perl 5.10+
When a Perl 5.10+ application spawns many concurrent threads, the goal is to maintain low latency while sharing complex data structures via threads::shared. The module guarantees sharing of scalars, arrays, and hashes, but the documentation notes that deep nested references may not preserve identity across threads, potentially causing contention.
Constraints arise from the interpreter’s per‑thread stack allocation and the implicit lock on shared data structures. On many platforms, the practical limit is around 100 active threads, yet the exact threshold can vary with system memory and CPU architecture.
Unresolved behavior centers on whether the threads::shared implementation allocates a new memory block for each thread when sharing deeply nested structures, and how this affects latency under high concurrency.
What is the observed latency impact when threads repeatedly dereference a deeply shared array reference? Does the interpreter allocate separate memory for each thread in such cases, and if so, under what conditions does this lead to measurable performance degradation?
perl