// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Implementation of runtime/debug.WriteHeapDump. Writes all
// objects in the heap plus additional info (roots, threads,
// finalizers, etc.) to a file.
// The format of the dumped file is described at
// https://golang.org/s/go14heapdump.
package runtime
import "unsafe"
//go:linkname runtime_debug_WriteHeapDump runtime/debug.WriteHeapDump
func runtime_debug_WriteHeapDump(fd uintptr) {
stopTheWorld("write heap dump")
systemstack(func() {
writeheapdump_m(fd)
})
startTheWorld()
}
const (
fieldKindEol = 0
fieldKindPtr = 1
fieldKindIface = 2
fieldKindEface = 3
tagEOF = 0
tagObject = 1
tagOtherRoot = 2
tagType = 3
tagGoroutine = 4
tagStackFrame = 5
tagParams = 6
tagFinalizer = 7
tagItab = 8
tagOSThread = 9
tagMemStats = 10
tagQueuedFinalizer = 11
tagData = 12
tagBSS = 13
tagDefer = 14
tagPanic = 15
tagMemProf = 16
tagAllocSample = 17
)
var dumpfd uintptr // fd to write the dump to.
var tmpbuf []byte
// buffer of pending write data
const (
bufSize = 4096
)
var buf [bufSize]byte
var nbuf uintptr
func dwrite(data unsafe.Pointer, len uintptr) {
if len == 0 {
return
}
if nbuf+len <= bufSize {
copy(buf[nbuf:], (*[bufSize]byte)(data)[:len])
nbuf += len
return
}
write(dumpfd, (unsafe.Pointer)(&buf), int32(nbuf))
if len >= bufSize {
write(dumpfd, data, int32(len))
nbuf = 0
} else {
copy(buf[:], (*[bufSize]byte)(data)[:len])
nbuf = len
}
}
func dwritebyte(b byte) {
dwrite(unsafe.Pointer(&b), 1)
}
func flush() {
write(dumpfd, (unsafe.Pointer)(&buf), int32(nbuf))
nbuf = 0
}
// Cache of types that have been serialized already.
// We use a type's hash field to pick a bucket.
// Inside a bucket, we keep a list of types that
// have been serialized so far, most recently used first.
// Note: when a bucket overflows we may end up
// serializing a type more than once. That's ok.
const (
typeCacheBuckets = 256
typeCacheAssoc = 4
)
type typeCacheBucket struct {
t [typeCacheAssoc]*_type
}
var typecache [typeCacheBuckets]typeCacheBucket
// dump a uint64 in a varint format parseable by encoding/binary
func dumpint(v uint64) {
var buf [10]byte
var n int
for v >= 0x80 {
buf[n] = byte(v | 0x80)
n++
v >>= 7
}
buf[n] = byte(v)
n++
dwrite(unsafe.Pointer(&buf), uintptr(n))
}
func dumpbool(b bool) {
if b {
dumpint(1)
} else {
dumpint(0)
}
}
// dump varint uint64 length followed by memory contents
func dumpmemrange(data unsafe.Pointer, len uintptr) {
dumpint(uint64(len))
dwrite(data, len)
}
func dumpslice(b []byte) {
dumpint(uint64(len(b)))
if len(b) > 0 {
dwrite(unsafe.Pointer(&b[0]), uintptr(len(b)))
}
}
func dumpstr(s string) {
sp := (*stringStruct)(unsafe.Pointer(&s))
dumpmemrange(sp.str, uintptr(sp.len))
}
// dump information for a type
func dumptype(t *_type) {
if t == nil {
return
}
// If we've definitely serialized the type before,
// no need to do it again.
b := &typecache[t.hash&(typeCacheBuckets-1)]
if t == b.t[0] {
return
}
for i := 1; i < typeCacheAssoc; i++ {
if t == b.t[i] {
// Move-to-front
for j := i; j > 0; j-- {
b.t[j] = b.t[j-1]
}
b.t[0] = t
return
}
}
// Might not have been dumped yet. Dump it and
// remember we did so.
for j := typeCacheAssoc - 1; j > 0; j-- {
b.t[j] = b.t[j-1]
}
b.t[0] = t
// dump the type
dumpint(tagType)
dumpint(uint64(uintptr(unsafe.Pointer(t))))
dumpint(uint64(t.size))
if t.x == nil || t.x.pkgpath == nil || t.x.name == nil {
dumpstr(*t._string)
} else {
pkgpath := (*stringStruct)(unsafe.Pointer(&t.x.pkgpath))
name := (*stringStruct)(unsafe.Pointer(&t.x.name))
dumpint(uint64(uintptr(pkgpath.len) + 1 + uintptr(name.len)))
dwrite(pkgpath.str, uintptr(pkgpath.len))
dwritebyte('.')
dwrite(name.str, uintptr(name.len))
}
dumpbool(t.kind&kindDirectIface == 0 || t.kind&kindNoPointers == 0)
}
// dump an object
func dumpobj(obj unsafe.Pointer, size uintptr, bv bitvector) {
dumpbvtypes(&bv, obj)
dumpint(tagObject)
dumpint(uint64(uintptr(obj)))
dumpmemrange(obj, size)
dumpfields(bv)
}
func dumpotherroot(description string, to unsafe.Pointer) {
dumpint(tagOtherRoot)
dumpstr(description)
dumpint(uint64(uintptr(to)))
}
func dumpfinalizer(obj unsafe.Pointer, fn *funcval, fint *_type, ot *ptrtype) {
dumpint(tagFinalizer)
dumpint(uint64(uintptr(obj)))
dumpint(uint64(uintptr(unsafe.Pointer(fn))))
dumpint(uint64(uintptr(unsafe.Pointer(fn.fn))))
dumpint(uint64(uintptr(unsafe.Pointer(fint))))
dumpint(uint64(uintptr(unsafe.Pointer(ot))))
}
type childInfo struct {
// Information passed up from the callee frame about
// the layout of the outargs region.
argoff uintptr // where the arguments start in the frame
arglen uintptr // size of args region
args bitvector // if args.n >= 0, pointer map of args region
sp *uint8 // callee sp
depth uintptr // depth in call stack (0 == most recent)
}
// dump kinds & offsets of interesting fields in bv
func dumpbv(cbv *bitvector, offset uintptr) {
bv := gobv(*cbv)
for i := uintptr(0); i < uintptr(bv.n); i++ {
if bv.bytedata[i/8]>>(i%8)&1 == 1 {
dumpint(fieldKindPtr)
dumpint(uint64(offset + i*ptrSize))
}
}
}
func dumpframe(s *stkframe, arg unsafe.Pointer) bool {
child := (*childInfo)(arg)
f := s.fn
// Figure out what we can about our stack map
pc := s.pc
if pc != f.entry {
pc--
}
pcdata := pcdatavalue(f, _PCDATA_StackMapIndex, pc)
if pcdata == -1 {
// We do not have a valid pcdata value but there might be a
// stackmap for this function. It is likely that we are looking
// at the function prologue, assume so and hope for the best.
pcdata = 0
}
stkmap := (*stackmap)(funcdata(f, _FUNCDATA_LocalsPointerMaps))
// Dump any types we will need to resolve Efaces.
if child.args.n >= 0 {
dumpbvtypes(&child.args, unsafe.Pointer(s.sp+child.argoff))
}
var bv bitvector
if stkmap != nil && stkmap.n > 0 {
bv = stackmapdata(stkmap, pcdata)
dumpbvtypes(&bv, unsafe.Pointer(s.varp-uintptr(bv.n*ptrSize)))
} else {
bv.n = -1
}
// Dump main body of stack frame.
dumpint(tagStackFrame)
dumpint(uint64(s.sp)) // lowest address in frame
dumpint(uint64(child.depth)) // # of frames deep on the stack
dumpint(uint64(uintptr(unsafe.Pointer(child.sp)))) // sp of child, or 0 if bottom of stack
dumpmemrange(unsafe.Pointer(s.sp), s.fp-s.sp) // frame contents
dumpint(uint64(f.entry))
dumpint(uint64(s.pc))
dumpint(uint64(s.continpc))
name := funcname(f)
if name == "" {
name = "unknown function"
}
dumpstr(name)
// Dump fields in the outargs section
if child.args.n >= 0 {
dumpbv(&child.args, child.argoff)
} else {
// conservative - everything might be a pointer
for off := child.argoff; off < child.argoff+child.arglen; off += ptrSize {
dumpint(fieldKindPtr)
dumpint(uint64(off))
}
}
// Dump fields in the local vars section
if stkmap == nil {
// No locals information, dump everything.
for off := child.arglen; off < s.varp-s.sp; off += ptrSize {
dumpint(fieldKindPtr)
dumpint(uint64(off))
}
} else if stkmap.n < 0 {
// Locals size information, dump just the locals.
size := uintptr(-stkmap.n)
for off := s.varp - size - s.sp; off < s.varp-s.sp; off += ptrSize {
dumpint(fieldKindPtr)
dumpint(uint64(off))
}
} else if stkmap.n > 0 {
// Locals bitmap information, scan just the pointers in
// locals.
dumpbv(&bv, s.varp-uintptr(bv.n)*ptrSize-s.sp)
}
dumpint(fieldKindEol)
// Record arg info for parent.
child.argoff = s.argp - s.fp
child.arglen = s.arglen
child.sp = (*uint8)(unsafe.Pointer(s.sp))
child.depth++
stkmap = (*stackmap)(funcdata(f, _FUNCDATA_ArgsPointerMaps))
if stkmap != nil {
child.args = stackmapdata(stkmap, pcdata)
} else {
child.args.n = -1
}
return true
}
func dumpgoroutine(gp *g) {
var sp, pc, lr uintptr
if gp.syscallsp != 0 {
sp = gp.syscallsp
pc = gp.syscallpc
lr = 0
} else {
sp = gp.sched.sp
pc = gp.sched.pc
lr = gp.sched.lr
}
dumpint(tagGoroutine)
dumpint(uint64(uintptr(unsafe.Pointer(gp))))
dumpint(uint64(sp))
dumpint(uint64(gp.goid))
dumpint(uint64(gp.gopc))
dumpint(uint64(readgstatus(gp)))
dumpbool(isSystemGoroutine(gp))
dumpbool(false) // isbackground
dumpint(uint64(gp.waitsince))
dumpstr(gp.waitreason)
dumpint(uint64(uintptr(gp.sched.ctxt)))
dumpint(uint64(uintptr(unsafe.Pointer(gp.m))))
dumpint(uint64(uintptr(unsafe.Pointer(gp._defer))))
dumpint(uint64(uintptr(unsafe.Pointer(gp._panic))))
// dump stack
var child childInfo
child.args.n = -1
child.arglen = 0
child.sp = nil
child.depth = 0
gentraceback(pc, sp, lr, gp, 0, nil, 0x7fffffff, dumpframe, noescape(unsafe.Pointer(&child)), 0)
// dump defer & panic records
for d := gp._defer; d != nil; d = d.link {
dumpint(tagDefer)
dumpint(uint64(uintptr(unsafe.Pointer(d))))
dumpint(uint64(uintptr(unsafe.Pointer(gp))))
dumpint(uint64(d.sp))
dumpint(uint64(d.pc))
dumpint(uint64(uintptr(unsafe.Pointer(d.fn))))
dumpint(uint64(uintptr(unsafe.Pointer(d.fn.fn))))
dumpint(uint64(uintptr(unsafe.Pointer(d.link))))
}
for p := gp._panic; p != nil; p = p.link {
dumpint(tagPanic)
dumpint(uint64(uintptr(unsafe.Pointer(p))))
dumpint(uint64(uintptr(unsafe.Pointer(gp))))
eface := (*eface)(unsafe.Pointer(&p.arg))
dumpint(uint64(uintptr(unsafe.Pointer(eface._type))))
dumpint(uint64(uintptr(unsafe.Pointer(eface.data))))
dumpint(0) // was p->defer, no longer recorded
dumpint(uint64(uintptr(unsafe.Pointer(p.link))))
}
}
func dumpgs() {
// goroutines & stacks
for i := 0; uintptr(i) < allglen; i++ {
gp := allgs[i]
status := readgstatus(gp) // The world is stopped so gp will not be in a scan state.
switch status {
default:
print("runtime: unexpected G.status ", hex(status), "\n")
throw("dumpgs in STW - bad status")
case _Gdead:
// ok
case _Grunnable,
_Gsyscall,
_Gwaiting:
dumpgoroutine(gp)
}
}
}
func finq_callback(fn *funcval, obj unsafe.Pointer, nret uintptr, fint *_type, ot *ptrtype) {
dumpint(tagQueuedFinalizer)
dumpint(uint64(uintptr(obj)))
dumpint(uint64(uintptr(unsafe.Pointer(fn))))
dumpint(uint64(uintptr(unsafe.Pointer(fn.fn))))
dumpint(uint64(uintptr(unsafe.Pointer(fint))))
dumpint(uint64(uintptr(unsafe.Pointer(ot))))
}
func dumproots() {
// TODO(mwhudson): dump datamask etc from all objects
// data segment
dumpbvtypes(&firstmoduledata.gcdatamask, unsafe.Pointer(firstmoduledata.data))
dumpint(tagData)
dumpint(uint64(firstmoduledata.data))
dumpmemrange(unsafe.Pointer(firstmoduledata.data), firstmoduledata.edata-firstmoduledata.data)
dumpfields(firstmoduledata.gcdatamask)
// bss segment
dumpbvtypes(&firstmoduledata.gcbssmask, unsafe.Pointer(firstmoduledata.bss))
dumpint(tagBSS)
dumpint(uint64(firstmoduledata.bss))
dumpmemrange(unsafe.Pointer(firstmoduledata.bss), firstmoduledata.ebss-firstmoduledata.bss)
dumpfields(firstmoduledata.gcbssmask)
// MSpan.types
allspans := h_allspans
for spanidx := uint32(0); spanidx < mheap_.nspan; spanidx++ {
s := allspans[spanidx]
if s.state == _MSpanInUse {
// Finalizers
for sp := s.specials; sp != nil; sp = sp.next {
if sp.kind != _KindSpecialFinalizer {
continue
}
spf := (*specialfinalizer)(unsafe.Pointer(sp))
p := unsafe.Pointer((uintptr(s.start) << _PageShift) + uintptr(spf.special.offset))
dumpfinalizer(p, spf.fn, spf.fint, spf.ot)
}
}
}
// Finalizer queue
iterate_finq(finq_callback)
}
// Bit vector of free marks.
// Needs to be as big as the largest number of objects per span.
var freemark [_PageSize / 8]bool
func dumpobjs() {
for i := uintptr(0); i < uintptr(mheap_.nspan); i++ {
s := h_allspans[i]
if s.state != _MSpanInUse {
continue
}
p := uintptr(s.start << _PageShift)
size := s.elemsize
n := (s.npages << _PageShift) / size
if n > uintptr(len(freemark)) {
throw("freemark array doesn't have enough entries")
}
for l := s.freelist; l.ptr() != nil; l = l.ptr().next {
freemark[(uintptr(l)-p)/size] = true
}
for j := uintptr(0); j < n; j, p = j+1, p+size {
if freemark[j] {
freemark[j] = false
continue
}
dumpobj(unsafe.Pointer(p), size, makeheapobjbv(p, size))
}
}
}
func dumpparams() {
dumpint(tagParams)
x := uintptr(1)
if *(*byte)(unsafe.Pointer(&x)) == 1 {
dumpbool(false) // little-endian ptrs
} else {
dumpbool(true) // big-endian ptrs
}
dumpint(ptrSize)
dumpint(uint64(mheap_.arena_start))
dumpint(uint64(mheap_.arena_used))
dumpint(thechar)
dumpstr(goexperiment)
dumpint(uint64(ncpu))
}
func itab_callback(tab *itab) {
t := tab._type
// Dump a map from itab* to the type of its data field.
// We want this map so we can deduce types of interface referents.
if t.kind&kindDirectIface == 0 {
// indirect - data slot is a pointer to t.
dumptype(t.ptrto)
dumpint(tagItab)
dumpint(uint64(uintptr(unsafe.Pointer(tab))))
dumpint(uint64(uintptr(unsafe.Pointer(t.ptrto))))
} else if t.kind&kindNoPointers == 0 {
// t is pointer-like - data slot is a t.
dumptype(t)
dumpint(tagItab)
dumpint(uint64(uintptr(unsafe.Pointer(tab))))
dumpint(uint64(uintptr(unsafe.Pointer(t))))
} else {
// Data slot is a scalar. Dump type just for fun.
// With pointer-only interfaces, this shouldn't happen.
dumptype(t)
dumpint(tagItab)
dumpint(uint64(uintptr(unsafe.Pointer(tab))))
dumpint(uint64(uintptr(unsafe.Pointer(t))))
}
}
func dumpitabs() {
iterate_itabs(itab_callback)
}
func dumpms() {
for mp := allm; mp != nil; mp = mp.alllink {
dumpint(tagOSThread)
dumpint(uint64(uintptr(unsafe.Pointer(mp))))
dumpint(uint64(mp.id))
dumpint(mp.procid)
}
}
func dumpmemstats() {
dumpint(tagMemStats)
dumpint(memstats.alloc)
dumpint(memstats.total_alloc)
dumpint(memstats.sys)
dumpint(memstats.nlookup)
dumpint(memstats.nmalloc)
dumpint(memstats.nfree)
dumpint(memstats.heap_alloc)
dumpint(memstats.heap_sys)
dumpint(memstats.heap_idle)
dumpint(memstats.heap_inuse)
dumpint(memstats.heap_released)
dumpint(memstats.heap_objects)
dumpint(memstats.stacks_inuse)
dumpint(memstats.stacks_sys)
dumpint(memstats.mspan_inuse)
dumpint(memstats.mspan_sys)
dumpint(memstats.mcache_inuse)
dumpint(memstats.mcache_sys)
dumpint(memstats.buckhash_sys)
dumpint(memstats.gc_sys)
dumpint(memstats.other_sys)
dumpint(memstats.next_gc)
dumpint(memstats.last_gc)
dumpint(memstats.pause_total_ns)
for i := 0; i < 256; i++ {
dumpint(memstats.pause_ns[i])
}
dumpint(uint64(memstats.numgc))
}
func dumpmemprof_callback(b *bucket, nstk uintptr, pstk *uintptr, size, allocs, frees uintptr) {
stk := (*[100000]uintptr)(unsafe.Pointer(pstk))
dumpint(tagMemProf)
dumpint(uint64(uintptr(unsafe.Pointer(b))))
dumpint(uint64(size))
dumpint(uint64(nstk))
for i := uintptr(0); i < nstk; i++ {
pc := stk[i]
f := findfunc(pc)
if f == nil {
var buf [64]byte
n := len(buf)
n--
buf[n] = ')'
if pc == 0 {
n--
buf[n] = '0'
} else {
for pc > 0 {
n--
buf[n] = "0123456789abcdef"[pc&15]
pc >>= 4
}
}
n--
buf[n] = 'x'
n--
buf[n] = '0'
n--
buf[n] = '('
dumpslice(buf[n:])
dumpstr("?")
dumpint(0)
} else {
dumpstr(funcname(f))
if i > 0 && pc > f.entry {
pc--
}
file, line := funcline(f, pc)
dumpstr(file)
dumpint(uint64(line))
}
}
dumpint(uint64(allocs))
dumpint(uint64(frees))
}
func dumpmemprof() {
iterate_memprof(dumpmemprof_callback)
allspans := h_allspans
for spanidx := uint32(0); spanidx < mheap_.nspan; spanidx++ {
s := allspans[spanidx]
if s.state != _MSpanInUse {
continue
}
for sp := s.specials; sp != nil; sp = sp.next {
if sp.kind != _KindSpecialProfile {
continue
}
spp := (*specialprofile)(unsafe.Pointer(sp))
p := uintptr(s.start<<_PageShift) + uintptr(spp.special.offset)
dumpint(tagAllocSample)
dumpint(uint64(p))
dumpint(uint64(uintptr(unsafe.Pointer(spp.b))))
}
}
}
var dumphdr = []byte("go1.5 heap dump\n")
func mdump() {
// make sure we're done sweeping
for i := uintptr(0); i < uintptr(mheap_.nspan); i++ {
s := h_allspans[i]
if s.state == _MSpanInUse {
mSpan_EnsureSwept(s)
}
}
memclr(unsafe.Pointer(&typecache), unsafe.Sizeof(typecache))
dwrite(unsafe.Pointer(&dumphdr[0]), uintptr(len(dumphdr)))
dumpparams()
dumpitabs()
dumpobjs()
dumpgs()
dumpms()
dumproots()
dumpmemstats()
dumpmemprof()
dumpint(tagEOF)
flush()
}
func writeheapdump_m(fd uintptr) {
_g_ := getg()
casgstatus(_g_.m.curg, _Grunning, _Gwaiting)
_g_.waitreason = "dumping heap"
// Update stats so we can dump them.
// As a side effect, flushes all the MCaches so the MSpan.freelist
// lists contain all the free objects.
updatememstats(nil)
// Set dump file.
dumpfd = fd
// Call dump routine.
mdump()
// Reset dump file.
dumpfd = 0
if tmpbuf != nil {
sysFree(unsafe.Pointer(&tmpbuf[0]), uintptr(len(tmpbuf)), &memstats.other_sys)
tmpbuf = nil
}
casgstatus(_g_.m.curg, _Gwaiting, _Grunning)
}
// dumpint() the kind & offset of each field in an object.
func dumpfields(bv bitvector) {
dumpbv(&bv, 0)
dumpint(fieldKindEol)
}
// The heap dump reader needs to be able to disambiguate
// Eface entries. So it needs to know every type that might
// appear in such an entry. The following routine accomplishes that.
// TODO(rsc, khr): Delete - no longer possible.
// Dump all the types that appear in the type field of
// any Eface described by this bit vector.
func dumpbvtypes(bv *bitvector, base unsafe.Pointer) {
}
func makeheapobjbv(p uintptr, size uintptr) bitvector {
// Extend the temp buffer if necessary.
nptr := size / ptrSize
if uintptr(len(tmpbuf)) < nptr/8+1 {
if tmpbuf != nil {
sysFree(unsafe.Pointer(&tmpbuf[0]), uintptr(len(tmpbuf)), &memstats.other_sys)
}
n := nptr/8 + 1
p := sysAlloc(n, &memstats.other_sys)
if p == nil {
throw("heapdump: out of memory")
}
tmpbuf = (*[1 << 30]byte)(p)[:n]
}
// Convert heap bitmap to pointer bitmap.
for i := uintptr(0); i < nptr/8+1; i++ {
tmpbuf[i] = 0
}
i := uintptr(0)
hbits := heapBitsForAddr(p)
for ; i < nptr; i++ {
if i >= 2 && !hbits.isMarked() {
break // end of object
}
if hbits.isPointer() {
tmpbuf[i/8] |= 1 << (i % 8)
}
hbits = hbits.next()
}
return bitvector{int32(i), &tmpbuf[0]}
}