diff --git a/src/gc.c b/src/gc.c index 97669e0acfe61..b54f64ffa00fd 100644 --- a/src/gc.c +++ b/src/gc.c @@ -371,6 +371,15 @@ static void jl_gc_run_finalizers_in_list(jl_task_t *ct, arraylist_t *list) JL_GC_POP(); } +static uint64_t finalizer_rngState[4]; + +void jl_rng_split(uint64_t to[4], uint64_t from[4]); + +JL_DLLEXPORT void jl_gc_init_finalizer_rng_state(void) +{ + jl_rng_split(finalizer_rngState, jl_current_task->rngState); +} + static void run_finalizers(jl_task_t *ct) { // Racy fast path: @@ -392,9 +401,16 @@ static void run_finalizers(jl_task_t *ct) } jl_atomic_store_relaxed(&jl_gc_have_pending_finalizers, 0); arraylist_new(&to_finalize, 0); + + uint64_t save_rngState[4]; + memcpy(&save_rngState[0], &ct->rngState[0], sizeof(save_rngState)); + jl_rng_split(ct->rngState, finalizer_rngState); + // This releases the finalizers lock. jl_gc_run_finalizers_in_list(ct, &copied_list); arraylist_free(&copied_list); + + memcpy(&ct->rngState[0], &save_rngState[0], sizeof(save_rngState)); } JL_DLLEXPORT void jl_gc_run_pending_finalizers(jl_task_t *ct) diff --git a/src/task.c b/src/task.c index 1dd4e76b8ba1c..b34ad464b4875 100644 --- a/src/task.c +++ b/src/task.c @@ -730,7 +730,7 @@ JL_DLLEXPORT uint64_t jl_tasklocal_genrandom(jl_task_t *task) JL_NOTSAFEPOINT return res; } -void rng_split(jl_task_t *from, jl_task_t *to) JL_NOTSAFEPOINT +void jl_rng_split(uint64_t to[4], uint64_t from[4]) JL_NOTSAFEPOINT { /* TODO: consider a less ad-hoc construction Ideally we could just use the output of the random stream to seed the initial @@ -748,10 +748,10 @@ void rng_split(jl_task_t *from, jl_task_t *to) JL_NOTSAFEPOINT 0x3688cf5d48899fa7 == hash(UInt(3))|0x01 0x867b4bb4c42e5661 == hash(UInt(4))|0x01 */ - to->rngState0 = 0x02011ce34bce797f * jl_tasklocal_genrandom(from); - to->rngState1 = 0x5a94851fb48a6e05 * jl_tasklocal_genrandom(from); - to->rngState2 = 0x3688cf5d48899fa7 * jl_tasklocal_genrandom(from); - to->rngState3 = 0x867b4bb4c42e5661 * jl_tasklocal_genrandom(from); + to[0] = 0x02011ce34bce797f * jl_genrandom(from); + to[1] = 0x5a94851fb48a6e05 * jl_genrandom(from); + to[2] = 0x3688cf5d48899fa7 * jl_genrandom(from); + to[3] = 0x867b4bb4c42e5661 * jl_genrandom(from); } JL_DLLEXPORT jl_task_t *jl_new_task(jl_function_t *start, jl_value_t *completion_future, size_t ssize) @@ -791,7 +791,7 @@ JL_DLLEXPORT jl_task_t *jl_new_task(jl_function_t *start, jl_value_t *completion // Inherit logger state from parent task t->logstate = ct->logstate; // Fork task-local random state from parent - rng_split(ct, t); + jl_rng_split(t->rngState, ct->rngState); // there is no active exception handler available on this stack yet t->eh = NULL; t->sticky = 1; diff --git a/stdlib/Random/src/RNGs.jl b/stdlib/Random/src/RNGs.jl index a50f633e68a9c..b16f0c5739dfd 100644 --- a/stdlib/Random/src/RNGs.jl +++ b/stdlib/Random/src/RNGs.jl @@ -400,6 +400,7 @@ end function __init__() seed!(GLOBAL_RNG) + ccall(:jl_gc_init_finalizer_rng_state, Cvoid, ()) end diff --git a/stdlib/Random/test/runtests.jl b/stdlib/Random/test/runtests.jl index c8be4c95cdaf2..339c47229f1e8 100644 --- a/stdlib/Random/test/runtests.jl +++ b/stdlib/Random/test/runtests.jl @@ -976,3 +976,26 @@ end @test minimum(m) >= 0.094 @test maximum(m) <= 0.106 end + +# issue #42752 +# test that running finalizers that launch tasks doesn't change RNG stream +function f42752(do_gc::Bool, cell = (()->Any[[]])()) + a = rand() + if do_gc + finalizer(cell[1]) do _ + @async nothing + end + cell[1] = nothing + GC.gc() + end + b = rand() + (a, b) +end +guardseed() do + for _ in 1:4 + Random.seed!(1) + val = f42752(false) + Random.seed!(1) + @test f42752(true) === val + end +end