From 2b193803d720f1cb5451af62d0805e7371851578 Mon Sep 17 00:00:00 2001 From: Ian Lance Taylor Date: Sat, 31 Oct 2015 23:48:19 +0000 Subject: [PATCH] runtime: If no split stacks, allocate stacks using mmap on 64-bit systems. When not using split stacks, libgo allocate large stacks for each goroutine. On a 64-bit system, libgo allocates a maximum of 128G for the Go heap, and allocates 4M for each stack. When the stacks are allocated from the Go heap, the result is that a program can only create 32K goroutines, which is not enough for an active Go server. This patch changes libgo to allocate the stacks using mmap directly, rather than allocating them out of the Go heap. This change is only done for 64-bit systems when not using split stacks. When using split stacks, the stacks are allocated using mmap directly anyhow. On a 32-bit system, there is no maximum size for the Go heap, or, rather, the maximum size is the available address space anyhow. Reviewed-on: https://go-review.googlesource.com/16531 From-SVN: r229636 --- gcc/go/gofrontend/MERGE | 2 +- libgo/runtime/proc.c | 17 +++++++++++++++-- 2 files changed, 16 insertions(+), 3 deletions(-) diff --git a/gcc/go/gofrontend/MERGE b/gcc/go/gofrontend/MERGE index 8eae1f4..d2c9492 100644 --- a/gcc/go/gofrontend/MERGE +++ b/gcc/go/gofrontend/MERGE @@ -1,4 +1,4 @@ -17cc10f7fb07e3f37448feaeb416b52618ae8bbb +1c1f226662a6c84eae83f8aaec3d4503e70be843 The first line of this file holds the git revision number of the last merge done from the gofrontend repository. diff --git a/libgo/runtime/proc.c b/libgo/runtime/proc.c index b5741c5..c25a217 100644 --- a/libgo/runtime/proc.c +++ b/libgo/runtime/proc.c @@ -2250,11 +2250,24 @@ runtime_malg(int32 stacksize, byte** ret_stack, size_t* ret_stacksize) __splitstack_block_signals_context(&newg->stack_context[0], &dont_block_signals, nil); #else - *ret_stack = runtime_mallocgc(stacksize, 0, FlagNoProfiling|FlagNoGC); + // In 64-bit mode, the maximum Go allocation space is + // 128G. Our stack size is 4M, which only permits 32K + // goroutines. In order to not limit ourselves, + // allocate the stacks out of separate memory. In + // 32-bit mode, the Go allocation space is all of + // memory anyhow. + if(sizeof(void*) == 8) { + void *p = runtime_SysAlloc(stacksize, &mstats.other_sys); + if(p == nil) + runtime_throw("runtime: cannot allocate memory for goroutine stack"); + *ret_stack = (byte*)p; + } else { + *ret_stack = runtime_mallocgc(stacksize, 0, FlagNoProfiling|FlagNoGC); + runtime_xadd(&runtime_stacks_sys, stacksize); + } *ret_stacksize = stacksize; newg->gcinitial_sp = *ret_stack; newg->gcstack_size = stacksize; - runtime_xadd(&runtime_stacks_sys, stacksize); #endif } return newg; -- 2.7.4