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runtime: run goroutines during init
Fixes #583. Fixes #1776. Fixes #2001. Fixes #2112. R=golang-dev, bradfitz, r, gri CC=golang-dev https://golang.org/cl/5265044
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@ -5109,12 +5109,6 @@ unspecified results if <code>A</code>'s initializer calls a function defined
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in another package that refers to <code>B</code>.
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</p>
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<p>
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Initialization code may contain "go" statements, but the functions
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they invoke do not begin execution until initialization of the entire
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program is complete. Therefore, all initialization code is run in a single
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goroutine.
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</p>
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<p>
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An <code>init</code> function cannot be referred to from anywhere
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in a program. In particular, <code>init</code> cannot be called explicitly,
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nor can a pointer to <code>init</code> be assigned to a function variable.
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@ -92,7 +92,6 @@ ok:
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TEXT runtime·mainstart(SB),7,$0
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CALL main·init(SB)
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CALL runtime·initdone(SB)
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CALL main·main(SB)
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PUSHL $0
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CALL runtime·exit(SB)
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@ -74,7 +74,6 @@ ok:
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TEXT runtime·mainstart(SB),7,$0
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CALL main·init(SB)
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CALL runtime·initdone(SB)
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CALL main·main(SB)
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PUSHQ $0
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CALL runtime·exit(SB)
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@ -63,7 +63,6 @@ TEXT _rt0_arm(SB),7,$-4
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TEXT runtime·mainstart(SB),7,$4
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BL main·init(SB)
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BL runtime·initdone(SB)
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EOR R0, R0
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MOVW R0, 0(R13)
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BL main·main(SB)
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@ -71,7 +71,6 @@ struct Sched {
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volatile uint32 atomic; // atomic scheduling word (see below)
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int32 predawn; // running initialization, don't run new g's.
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int32 profilehz; // cpu profiling rate
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Note stopped; // one g can set waitstop and wait here for m's to stop
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@ -202,8 +201,8 @@ runtime·schedinit(void)
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}
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setmcpumax(runtime·gomaxprocs);
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runtime·singleproc = runtime·gomaxprocs == 1;
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runtime·sched.predawn = 1;
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mstats.enablegc = 1;
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m->nomemprof--;
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}
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@ -227,22 +226,6 @@ schedunlock(void)
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runtime·notewakeup(&m->havenextg);
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}
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// Called after main·init_function; main·main will be called on return.
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void
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runtime·initdone(void)
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{
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// Let's go.
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runtime·sched.predawn = 0;
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mstats.enablegc = 1;
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// If main·init_function started other goroutines,
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// kick off new m's to handle them, like ready
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// would have, had it not been pre-dawn.
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schedlock();
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matchmg();
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schedunlock();
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}
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void
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runtime·goexit(void)
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{
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@ -467,8 +450,7 @@ readylocked(G *g)
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g->status = Grunnable;
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gput(g);
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if(!runtime·sched.predawn)
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matchmg();
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matchmg();
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}
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static void
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@ -793,9 +775,6 @@ schedule(G *gp)
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schedlock();
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if(gp != nil) {
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if(runtime·sched.predawn)
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runtime·throw("init rescheduling");
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// Just finished running gp.
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gp->m = nil;
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runtime·sched.grunning--;
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@ -893,9 +872,6 @@ runtime·entersyscall(void)
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{
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uint32 v;
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if(runtime·sched.predawn)
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return;
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// Leave SP around for gc and traceback.
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runtime·gosave(&g->sched);
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g->gcsp = g->sched.sp;
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@ -947,9 +923,6 @@ runtime·exitsyscall(void)
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{
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uint32 v;
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if(runtime·sched.predawn)
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return;
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// Fast path.
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// If we can do the mcpu++ bookkeeping and
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// find that we still have mcpu <= mcpumax, then we can
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@ -1513,8 +1486,6 @@ runtime·Gosched(void)
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void
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runtime·LockOSThread(void)
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{
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if(runtime·sched.predawn)
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runtime·throw("cannot wire during init");
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m->lockedg = g;
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g->lockedm = m;
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}
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44
test/init1.go
Normal file
44
test/init1.go
Normal file
@ -0,0 +1,44 @@
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// $G $D/$F.go && $L $F.$A && ./$A.out
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// Copyright 2011 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Test that goroutines and garbage collection run during init.
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package main
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import "runtime"
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var x []byte
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func init() {
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c := make(chan int)
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go send(c)
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<-c
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const chunk = 1<<20
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runtime.UpdateMemStats()
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sys := runtime.MemStats.Sys
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b := make([]byte, chunk)
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for i := range b {
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b[i] = byte(i%10 + '0')
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}
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s := string(b)
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for i := 0; i < 1000; i++ {
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x = []byte(s)
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}
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runtime.UpdateMemStats()
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sys1 := runtime.MemStats.Sys
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if sys1-sys > chunk*50 {
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println("allocated 1000 chunks of", chunk, "and used ", sys1-sys, "memory")
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}
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}
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func send(c chan int) {
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c <- 1
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}
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func main() {
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}
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