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// 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/go15heapdump.
package runtime
import (
"internal/abi"
"internal/goarch"
"internal/goexperiment"
"unsafe"
)
//go:linkname runtime_debug_WriteHeapDump runtime/debug.WriteHeapDump
func runtime_debug_WriteHeapDump(fd uintptr) {
stw := stopTheWorld(stwWriteHeapDump)
// Keep m on this G's stack instead of the system stack.
// Both readmemstats_m and writeheapdump_m have pretty large
// peak stack depths and we risk blowing the system stack.
// This is safe because the world is stopped, so we don't
// need to worry about anyone shrinking and therefore moving
// our stack.
var m MemStats
systemstack(func() {
// Call readmemstats_m here instead of deeper in
// writeheapdump_m because we might blow the system stack
// otherwise.
readmemstats_m(&m)
writeheapdump_m(fd, &m)
})
startTheWorld(stw)
}
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) {
dumpmemrange(unsafe.Pointer(unsafe.StringData(s)), uintptr(len(s)))
}
// 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_))
rt := toRType(t)
if x := t.Uncommon(); x == nil || rt.nameOff(x.PkgPath).Name() == "" {
dumpstr(rt.string())
} else {
pkgpath := rt.nameOff(x.PkgPath).Name()
name := rt.name()
dumpint(uint64(uintptr(len(pkgpath)) + 1 + uintptr(len(name))))
dwrite(unsafe.Pointer(unsafe.StringData(pkgpath)), uintptr(len(pkgpath)))
dwritebyte('.')
dwrite(unsafe.Pointer(unsafe.StringData(name)), uintptr(len(name)))
}
dumpbool(t.Kind_&kindDirectIface == 0 || t.PtrBytes != 0)
}
// dump an object.
func dumpobj(obj unsafe.Pointer, size uintptr, bv bitvector) {
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) {
for i := uintptr(0); i < uintptr(cbv.n); i++ {
if cbv.ptrbit(i) == 1 {
dumpint(fieldKindPtr)
dumpint(uint64(offset + i*goarch.PtrSize))
}
}
}
func dumpframe(s *stkframe, child *childInfo) {
f := s.fn
// Figure out what we can about our stack map
pc := s.pc
pcdata := int32(-1) // Use the entry map at function entry
if pc != f.entry() {
pc--
pcdata = pcdatavalue(f, abi.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, abi.FUNCDATA_LocalsPointerMaps))
var bv bitvector
if stkmap != nil && stkmap.n > 0 {
bv = stackmapdata(stkmap, pcdata)
} 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 += goarch.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 += goarch.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 += goarch.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)*goarch.PtrSize-s.sp)
}
dumpint(fieldKindEol)
// Record arg info for parent.
child.argoff = s.argp - s.fp
child.arglen = s.argBytes()
child.sp = (*uint8)(unsafe.Pointer(s.sp))
child.depth++
stkmap = (*stackmap)(funcdata(f, abi.FUNCDATA_ArgsPointerMaps))
if stkmap != nil {
child.args = stackmapdata(stkmap, pcdata)
} else {
child.args.n = -1
}
return
}
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(gp.goid)
dumpint(uint64(gp.gopc))
dumpint(uint64(readgstatus(gp)))
dumpbool(isSystemGoroutine(gp, false))
dumpbool(false) // isbackground
dumpint(uint64(gp.waitsince))
dumpstr(gp.waitreason.String())
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
var u unwinder
for u.initAt(pc, sp, lr, gp, 0); u.valid(); u.next() {
dumpframe(&u.frame, &child)
}
// 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))
fn := *(**funcval)(unsafe.Pointer(&d.fn))
dumpint(uint64(uintptr(unsafe.Pointer(fn))))
if d.fn == nil {
// d.fn can be nil for open-coded defers
dumpint(uint64(0))
} else {
dumpint(uint64(uintptr(unsafe.Pointer(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 := efaceOf(&p.arg)
dumpint(uint64(uintptr(unsafe.Pointer(eface._type))))
dumpint(uint64(uintptr(eface.data)))
dumpint(0) // was p->defer, no longer recorded
dumpint(uint64(uintptr(unsafe.Pointer(p.link))))
}
}
func dumpgs() {
assertWorldStopped()
// goroutines & stacks
forEachG(func(gp *g) {
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() {
// To protect mheap_.allspans.
assertWorldStopped()
// TODO(mwhudson): dump datamask etc from all objects
// data segment
dumpint(tagData)
dumpint(uint64(firstmoduledata.data))
dumpmemrange(unsafe.Pointer(firstmoduledata.data), firstmoduledata.edata-firstmoduledata.data)
dumpfields(firstmoduledata.gcdatamask)
// bss segment
dumpint(tagBSS)
dumpint(uint64(firstmoduledata.bss))
dumpmemrange(unsafe.Pointer(firstmoduledata.bss), firstmoduledata.ebss-firstmoduledata.bss)
dumpfields(firstmoduledata.gcbssmask)
// mspan.types
for _, s := range mheap_.allspans {
if s.state.get() == mSpanInUse {
// Finalizers
for sp := s.specials; sp != nil; sp = sp.next {
if sp.kind != _KindSpecialFinalizer {
continue
}
spf := (*specialfinalizer)(unsafe.Pointer(sp))
p := unsafe.Pointer(s.base() + 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() {
// To protect mheap_.allspans.
assertWorldStopped()
for _, s := range mheap_.allspans {
if s.state.get() != mSpanInUse {
continue
}
p := s.base()
size := s.elemsize
n := (s.npages << _PageShift) / size
if n > uintptr(len(freemark)) {
throw("freemark array doesn't have enough entries")
}
for freeIndex := uint16(0); freeIndex < s.nelems; freeIndex++ {
if s.isFree(uintptr(freeIndex)) {
freemark[freeIndex] = 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(goarch.PtrSize)
var arenaStart, arenaEnd uintptr
for i1 := range mheap_.arenas {
if mheap_.arenas[i1] == nil {
continue
}
for i, ha := range mheap_.arenas[i1] {
if ha == nil {
continue
}
base := arenaBase(arenaIdx(i1)<<arenaL1Shift | arenaIdx(i))
if arenaStart == 0 || base < arenaStart {
arenaStart = base
}
if base+heapArenaBytes > arenaEnd {
arenaEnd = base + heapArenaBytes
}
}
}
dumpint(uint64(arenaStart))
dumpint(uint64(arenaEnd))
dumpstr(goarch.GOARCH)
dumpstr(buildVersion)
dumpint(uint64(ncpu))
}
func itab_callback(tab *itab) {
t := tab._type
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)
}
}
//go:systemstack
func dumpmemstats(m *MemStats) {
assertWorldStopped()
// These ints should be identical to the exported
// MemStats structure and should be ordered the same
// way too.
dumpint(tagMemStats)
dumpint(m.Alloc)
dumpint(m.TotalAlloc)
dumpint(m.Sys)
dumpint(m.Lookups)
dumpint(m.Mallocs)
dumpint(m.Frees)
dumpint(m.HeapAlloc)
dumpint(m.HeapSys)
dumpint(m.HeapIdle)
dumpint(m.HeapInuse)
dumpint(m.HeapReleased)
dumpint(m.HeapObjects)
dumpint(m.StackInuse)
dumpint(m.StackSys)
dumpint(m.MSpanInuse)
dumpint(m.MSpanSys)
dumpint(m.MCacheInuse)
dumpint(m.MCacheSys)
dumpint(m.BuckHashSys)
dumpint(m.GCSys)
dumpint(m.OtherSys)
dumpint(m.NextGC)
dumpint(m.LastGC)
dumpint(m.PauseTotalNs)
for i := 0; i < 256; i++ {
dumpint(m.PauseNs[i])
}
dumpint(uint64(m.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.valid() {
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() {
// To protect mheap_.allspans.
assertWorldStopped()
iterate_memprof(dumpmemprof_callback)
for _, s := range mheap_.allspans {
if s.state.get() != mSpanInUse {
continue
}
for sp := s.specials; sp != nil; sp = sp.next {
if sp.kind != _KindSpecialProfile {
continue
}
spp := (*specialprofile)(unsafe.Pointer(sp))
p := s.base() + uintptr(spp.special.offset)
dumpint(tagAllocSample)
dumpint(uint64(p))
dumpint(uint64(uintptr(unsafe.Pointer(spp.b))))
}
}
}
var dumphdr = []byte("go1.7 heap dump\n")
func mdump(m *MemStats) {
assertWorldStopped()
// make sure we're done sweeping
for _, s := range mheap_.allspans {
if s.state.get() == mSpanInUse {
s.ensureSwept()
}
}
memclrNoHeapPointers(unsafe.Pointer(&typecache), unsafe.Sizeof(typecache))
dwrite(unsafe.Pointer(&dumphdr[0]), uintptr(len(dumphdr)))
dumpparams()
dumpitabs()
dumpobjs()
dumpgs()
dumpms()
dumproots()
dumpmemstats(m)
dumpmemprof()
dumpint(tagEOF)
flush()
}
func writeheapdump_m(fd uintptr, m *MemStats) {
assertWorldStopped()
gp := getg()
casGToWaiting(gp.m.curg, _Grunning, waitReasonDumpingHeap)
// Set dump file.
dumpfd = fd
// Call dump routine.
mdump(m)
// Reset dump file.
dumpfd = 0
if tmpbuf != nil {
sysFree(unsafe.Pointer(&tmpbuf[0]), uintptr(len(tmpbuf)), &memstats.other_sys)
tmpbuf = nil
}
casgstatus(gp.m.curg, _Gwaiting, _Grunning)
}
// dumpint() the kind & offset of each field in an object.
func dumpfields(bv bitvector) {
dumpbv(&bv, 0)
dumpint(fieldKindEol)
}
func makeheapobjbv(p uintptr, size uintptr) bitvector {
// Extend the temp buffer if necessary.
nptr := size / goarch.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
}
if goexperiment.AllocHeaders {
s := spanOf(p)
tp := s.typePointersOf(p, size)
for {
var addr uintptr
if tp, addr = tp.next(p + size); addr == 0 {
break
}
i := (addr - p) / goarch.PtrSize
tmpbuf[i/8] |= 1 << (i % 8)
}
} else {
hbits := heapBitsForAddr(p, size)
for {
var addr uintptr
hbits, addr = hbits.next()
if addr == 0 {
break
}
i := (addr - p) / goarch.PtrSize
tmpbuf[i/8] |= 1 << (i % 8)
}
}
return bitvector{int32(nptr), &tmpbuf[0]}
}