Compiler is the name of the compiler toolchain that built the running binary. Known toolchains are:
gc Also known as cmd/compile. gccgo The gccgo front end, part of the GCC compiler suite.
const Compiler = "gc"
GOARCH is the running program's architecture target: 386, amd64, arm, or s390x.
const GOARCH string = sys.GOARCH
GOOS is the running program's operating system target: one of darwin, freebsd, linux, and so on.
const GOOS string = sys.GOOS
MemProfileRate controls the fraction of memory allocations that are recorded and reported in the memory profile. The profiler aims to sample an average of one allocation per MemProfileRate bytes allocated.
To include every allocated block in the profile, set MemProfileRate to 1. To turn off profiling entirely, set MemProfileRate to 0.
The tools that process the memory profiles assume that the profile rate is constant across the lifetime of the program and equal to the current value. Programs that change the memory profiling rate should do so just once, as early as possible in the execution of the program (for example, at the beginning of main).
var MemProfileRate int = 512 * 1024
func BlockProfile(p []BlockProfileRecord) (n int, ok bool)
BlockProfile returns n, the number of records in the current blocking profile. If len(p) >= n, BlockProfile copies the profile into p and returns n, true. If len(p) < n, BlockProfile does not change p and returns n, false.
Most clients should use the runtime/pprof package or the testing package's -test.blockprofile flag instead of calling BlockProfile directly.
func Breakpoint()
Breakpoint executes a breakpoint trap.
func CPUProfile() []byte
CPUProfile returns the next chunk of binary CPU profiling stack trace data, blocking until data is available. If profiling is turned off and all the profile data accumulated while it was on has been returned, CPUProfile returns nil. The caller must save the returned data before calling CPUProfile again.
Most clients should use the runtime/pprof package or the testing package's -test.cpuprofile flag instead of calling CPUProfile directly.
func Caller(skip int) (pc uintptr, file string, line int, ok bool)
Caller reports file and line number information about function invocations on the calling goroutine's stack. The argument skip is the number of stack frames to ascend, with 0 identifying the caller of Caller. (For historical reasons the meaning of skip differs between Caller and Callers.) The return values report the program counter, file name, and line number within the file of the corresponding call. The boolean ok is false if it was not possible to recover the information.
func Callers(skip int, pc []uintptr) int
Callers fills the slice pc with the return program counters of function invocations on the calling goroutine's stack. The argument skip is the number of stack frames to skip before recording in pc, with 0 identifying the frame for Callers itself and 1 identifying the caller of Callers. It returns the number of entries written to pc.
Note that since each slice entry pc[i] is a return program counter, looking up the file and line for pc[i] (for example, using (*Func).FileLine) will normally return the file and line number of the instruction immediately following the call. To easily look up file/line information for the call sequence, use Frames.
func GC()
GC runs a garbage collection and blocks the caller until the garbage collection is complete. It may also block the entire program.
func GOMAXPROCS(n int) int
GOMAXPROCS sets the maximum number of CPUs that can be executing simultaneously and returns the previous setting. If n < 1, it does not change the current setting. The number of logical CPUs on the local machine can be queried with NumCPU. This call will go away when the scheduler improves.
func GOROOT() string
GOROOT returns the root of the Go tree. It uses the GOROOT environment variable, if set, or else the root used during the Go build.
func Goexit()
Goexit terminates the goroutine that calls it. No other goroutine is affected. Goexit runs all deferred calls before terminating the goroutine. Because Goexit is not panic, however, any recover calls in those deferred functions will return nil.
Calling Goexit from the main goroutine terminates that goroutine without func main returning. Since func main has not returned, the program continues execution of other goroutines. If all other goroutines exit, the program crashes.
func GoroutineProfile(p []StackRecord) (n int, ok bool)
GoroutineProfile returns n, the number of records in the active goroutine stack profile. If len(p) >= n, GoroutineProfile copies the profile into p and returns n, true. If len(p) < n, GoroutineProfile does not change p and returns n, false.
Most clients should use the runtime/pprof package instead of calling GoroutineProfile directly.
func Gosched()
Gosched yields the processor, allowing other goroutines to run. It does not suspend the current goroutine, so execution resumes automatically.
func KeepAlive(interface{})
KeepAlive marks its argument as currently reachable. This ensures that the object is not freed, and its finalizer is not run, before the point in the program where KeepAlive is called.
A very simplified example showing where KeepAlive is required:
type File struct { d int }
d, err := syscall.Open("/file/path", syscall.O_RDONLY, 0)
// ... do something if err != nil ...
p := &File{d}
runtime.SetFinalizer(p, func(p *File) { syscall.Close(p.d) })
var buf [10]byte
n, err := syscall.Read(p.d, buf[:])
// Ensure p is not finalized until Read returns.
runtime.KeepAlive(p)
// No more uses of p after this point.
Without the KeepAlive call, the finalizer could run at the start of syscall.Read, closing the file descriptor before syscall.Read makes the actual system call.
func LockOSThread()
LockOSThread wires the calling goroutine to its current operating system thread. Until the calling goroutine exits or calls UnlockOSThread, it will always execute in that thread, and no other goroutine can.
func MemProfile(p []MemProfileRecord, inuseZero bool) (n int, ok bool)
MemProfile returns a profile of memory allocated and freed per allocation site.
MemProfile returns n, the number of records in the current memory profile. If len(p) >= n, MemProfile copies the profile into p and returns n, true. If len(p) < n, MemProfile does not change p and returns n, false.
If inuseZero is true, the profile includes allocation records where r.AllocBytes > 0 but r.AllocBytes == r.FreeBytes. These are sites where memory was allocated, but it has all been released back to the runtime.
The returned profile may be up to two garbage collection cycles old. This is to avoid skewing the profile toward allocations; because allocations happen in real time but frees are delayed until the garbage collector performs sweeping, the profile only accounts for allocations that have had a chance to be freed by the garbage collector.
Most clients should use the runtime/pprof package or the testing package's -test.memprofile flag instead of calling MemProfile directly.
func MutexProfile(p []BlockProfileRecord) (n int, ok bool)
MutexProfile returns n, the number of records in the current mutex profile. If len(p) >= n, MutexProfile copies the profile into p and returns n, true. Otherwise, MutexProfile does not change p, and returns n, false.
Most clients should use the runtime/pprof package instead of calling MutexProfile directly.
func NumCPU() int
NumCPU returns the number of logical CPUs usable by the current process.
The set of available CPUs is checked by querying the operating system at process startup. Changes to operating system CPU allocation after process startup are not reflected.
func NumCgoCall() int64
NumCgoCall returns the number of cgo calls made by the current process.
func NumGoroutine() int
NumGoroutine returns the number of goroutines that currently exist.
func ReadMemStats(m *MemStats)
ReadMemStats populates m with memory allocator statistics.
The returned memory allocator statistics are up to date as of the call to ReadMemStats. This is in contrast with a heap profile, which is a snapshot as of the most recently completed garbage collection cycle.
func ReadTrace() []byte
ReadTrace returns the next chunk of binary tracing data, blocking until data is available. If tracing is turned off and all the data accumulated while it was on has been returned, ReadTrace returns nil. The caller must copy the returned data before calling ReadTrace again. ReadTrace must be called from one goroutine at a time.
func SetBlockProfileRate(rate int)
SetBlockProfileRate controls the fraction of goroutine blocking events that are reported in the blocking profile. The profiler aims to sample an average of one blocking event per rate nanoseconds spent blocked.
To include every blocking event in the profile, pass rate = 1. To turn off profiling entirely, pass rate <= 0.
func SetCPUProfileRate(hz int)
SetCPUProfileRate sets the CPU profiling rate to hz samples per second. If hz <= 0, SetCPUProfileRate turns off profiling. If the profiler is on, the rate cannot be changed without first turning it off.
Most clients should use the runtime/pprof package or the testing package's -test.cpuprofile flag instead of calling SetCPUProfileRate directly.
func SetCgoTraceback(version int, traceback, context, symbolizer unsafe.Pointer)
SetCgoTraceback records three C functions to use to gather traceback information from C code and to convert that traceback information into symbolic information. These are used when printing stack traces for a program that uses cgo.
The traceback and context functions may be called from a signal handler, and must therefore use only async-signal safe functions. The symbolizer function may be called while the program is crashing, and so must be cautious about using memory. None of the functions may call back into Go.
The context function will be called with a single argument, a pointer to a struct:
struct {
Context uintptr
}
In C syntax, this struct will be
struct {
uintptr_t Context;
};
If the Context field is 0, the context function is being called to record the current traceback context. It should record in the Context field whatever information is needed about the current point of execution to later produce a stack trace, probably the stack pointer and PC. In this case the context function will be called from C code.
If the Context field is not 0, then it is a value returned by a previous call to the context function. This case is called when the context is no longer needed; that is, when the Go code is returning to its C code caller. This permits the context function to release any associated resources.
While it would be correct for the context function to record a complete a stack trace whenever it is called, and simply copy that out in the traceback function, in a typical program the context function will be called many times without ever recording a traceback for that context. Recording a complete stack trace in a call to the context function is likely to be inefficient.
The traceback function will be called with a single argument, a pointer to a struct:
struct {
Context uintptr
SigContext uintptr
Buf *uintptr
Max uintptr
}
In C syntax, this struct will be
struct {
uintptr_t Context;
uintptr_t SigContext;
uintptr_t* Buf;
uintptr_t Max;
};
The Context field will be zero to gather a traceback from the current program execution point. In this case, the traceback function will be called from C code.
Otherwise Context will be a value previously returned by a call to the context function. The traceback function should gather a stack trace from that saved point in the program execution. The traceback function may be called from an execution thread other than the one that recorded the context, but only when the context is known to be valid and unchanging. The traceback function may also be called deeper in the call stack on the same thread that recorded the context. The traceback function may be called multiple times with the same Context value; it will usually be appropriate to cache the result, if possible, the first time this is called for a specific context value.
If the traceback function is called from a signal handler on a Unix system, SigContext will be the signal context argument passed to the signal handler (a C ucontext_t* cast to uintptr_t). This may be used to start tracing at the point where the signal occurred. If the traceback function is not called from a signal handler, SigContext will be zero.
Buf is where the traceback information should be stored. It should be PC values, such that Buf[0] is the PC of the caller, Buf[1] is the PC of that function's caller, and so on. Max is the maximum number of entries to store. The function should store a zero to indicate the top of the stack, or that the caller is on a different stack, presumably a Go stack.
Unlike runtime.Callers, the PC values returned should, when passed to the symbolizer function, return the file/line of the call instruction. No additional subtraction is required or appropriate.
The symbolizer function will be called with a single argument, a pointer to a struct:
struct {
PC uintptr // program counter to fetch information for
File *byte // file name (NUL terminated)
Lineno uintptr // line number
Func *byte // function name (NUL terminated)
Entry uintptr // function entry point
More uintptr // set non-zero if more info for this PC
Data uintptr // unused by runtime, available for function
}
In C syntax, this struct will be
struct {
uintptr_t PC;
char* File;
uintptr_t Lineno;
char* Func;
uintptr_t Entry;
uintptr_t More;
uintptr_t Data;
};
The PC field will be a value returned by a call to the traceback function.
The first time the function is called for a particular traceback, all the fields except PC will be 0. The function should fill in the other fields if possible, setting them to 0/nil if the information is not available. The Data field may be used to store any useful information across calls. The More field should be set to non-zero if there is more information for this PC, zero otherwise. If More is set non-zero, the function will be called again with the same PC, and may return different information (this is intended for use with inlined functions). If More is zero, the function will be called with the next PC value in the traceback. When the traceback is complete, the function will be called once more with PC set to zero; this may be used to free any information. Each call will leave the fields of the struct set to the same values they had upon return, except for the PC field when the More field is zero. The function must not keep a copy of the struct pointer between calls.
When calling SetCgoTraceback, the version argument is the version number of the structs that the functions expect to receive. Currently this must be zero.
The symbolizer function may be nil, in which case the results of the traceback function will be displayed as numbers. If the traceback function is nil, the symbolizer function will never be called. The context function may be nil, in which case the traceback function will only be called with the context field set to zero. If the context function is nil, then calls from Go to C to Go will not show a traceback for the C portion of the call stack.
SetCgoTraceback should be called only once, ideally from an init function.
func SetFinalizer(obj interface{}, finalizer interface{})
SetFinalizer sets the finalizer associated with obj to the provided finalizer function. When the garbage collector finds an unreachable block with an associated finalizer, it clears the association and runs finalizer(obj) in a separate goroutine. This makes obj reachable again, but now without an associated finalizer. Assuming that SetFinalizer is not called again, the next time the garbage collector sees that obj is unreachable, it will free obj.
SetFinalizer(obj, nil) clears any finalizer associated with obj.
The argument obj must be a pointer to an object allocated by calling new, by taking the address of a composite literal, or by taking the address of a local variable. The argument finalizer must be a function that takes a single argument to which obj's type can be assigned, and can have arbitrary ignored return values. If either of these is not true, SetFinalizer may abort the program.
Finalizers are run in dependency order: if A points at B, both have finalizers, and they are otherwise unreachable, only the finalizer for A runs; once A is freed, the finalizer for B can run. If a cyclic structure includes a block with a finalizer, that cycle is not guaranteed to be garbage collected and the finalizer is not guaranteed to run, because there is no ordering that respects the dependencies.
The finalizer for obj is scheduled to run at some arbitrary time after obj becomes unreachable. There is no guarantee that finalizers will run before a program exits, so typically they are useful only for releasing non-memory resources associated with an object during a long-running program. For example, an os.File object could use a finalizer to close the associated operating system file descriptor when a program discards an os.File without calling Close, but it would be a mistake to depend on a finalizer to flush an in-memory I/O buffer such as a bufio.Writer, because the buffer would not be flushed at program exit.
It is not guaranteed that a finalizer will run if the size of *obj is zero bytes.
It is not guaranteed that a finalizer will run for objects allocated in initializers for package-level variables. Such objects may be linker-allocated, not heap-allocated.
A finalizer may run as soon as an object becomes unreachable. In order to use finalizers correctly, the program must ensure that the object is reachable until it is no longer required. Objects stored in global variables, or that can be found by tracing pointers from a global variable, are reachable. For other objects, pass the object to a call of the KeepAlive function to mark the last point in the function where the object must be reachable.
For example, if p points to a struct that contains a file descriptor d, and p has a finalizer that closes that file descriptor, and if the last use of p in a function is a call to syscall.Write(p.d, buf, size), then p may be unreachable as soon as the program enters syscall.Write. The finalizer may run at that moment, closing p.d, causing syscall.Write to fail because it is writing to a closed file descriptor (or, worse, to an entirely different file descriptor opened by a different goroutine). To avoid this problem, call runtime.KeepAlive(p) after the call to syscall.Write.
A single goroutine runs all finalizers for a program, sequentially. If a finalizer must run for a long time, it should do so by starting a new goroutine.
func SetMutexProfileFraction(rate int) int
SetMutexProfileFraction controls the fraction of mutex contention events that are reported in the mutex profile. On average 1/rate events are reported. The previous rate is returned.
To turn off profiling entirely, pass rate 0. To just read the current rate, pass rate -1. (For n>1 the details of sampling may change.)
func Stack(buf []byte, all bool) int
Stack formats a stack trace of the calling goroutine into buf and returns the number of bytes written to buf. If all is true, Stack formats stack traces of all other goroutines into buf after the trace for the current goroutine.
func StartTrace() error
StartTrace enables tracing for the current process. While tracing, the data will be buffered and available via ReadTrace. StartTrace returns an error if tracing is already enabled. Most clients should use the runtime/trace package or the testing package's -test.trace flag instead of calling StartTrace directly.
func StopTrace()
StopTrace stops tracing, if it was previously enabled. StopTrace only returns after all the reads for the trace have completed.
func ThreadCreateProfile(p []StackRecord) (n int, ok bool)
ThreadCreateProfile returns n, the number of records in the thread creation profile. If len(p) >= n, ThreadCreateProfile copies the profile into p and returns n, true. If len(p) < n, ThreadCreateProfile does not change p and returns n, false.
Most clients should use the runtime/pprof package instead of calling ThreadCreateProfile directly.
func UnlockOSThread()
UnlockOSThread unwires the calling goroutine from its fixed operating system thread. If the calling goroutine has not called LockOSThread, UnlockOSThread is a no-op.
func Version() string
Version returns the Go tree's version string. It is either the commit hash and date at the time of the build or, when possible, a release tag like "go1.3".
BlockProfileRecord describes blocking events originated at a particular call sequence (stack trace).
type BlockProfileRecord struct {
Count int64
Cycles int64
StackRecord
}
The Error interface identifies a run time error.
type Error interface {
error
// RuntimeError is a no-op function but
// serves to distinguish types that are run time
// errors from ordinary errors: a type is a
// run time error if it has a RuntimeError method.
RuntimeError()
}
Frame is the information returned by Frames for each call frame.
type Frame struct {
// Program counter for this frame; multiple frames may have
// the same PC value.
PC uintptr
// Func for this frame; may be nil for non-Go code or fully
// inlined functions.
Func *Func
// Function name, file name, and line number for this call frame.
// May be the empty string or zero if not known.
// If Func is not nil then Function == Func.Name().
Function string
File string
Line int
// Entry point for the function; may be zero if not known.
// If Func is not nil then Entry == Func.Entry().
Entry uintptr
}
Frames may be used to get function/file/line information for a slice of PC values returned by Callers.
type Frames struct {
// contains filtered or unexported fields
}
func CallersFrames(callers []uintptr) *Frames
CallersFrames takes a slice of PC values returned by Callers and prepares to return function/file/line information. Do not change the slice until you are done with the Frames.
func (ci *Frames) Next() (frame Frame, more bool)
Next returns frame information for the next caller. If more is false, there are no more callers (the Frame value is valid).
A Func represents a Go function in the running binary.
type Func struct {
// contains filtered or unexported fields
}
func FuncForPC(pc uintptr) *Func
FuncForPC returns a *Func describing the function that contains the given program counter address, or else nil.
func (f *Func) Entry() uintptr
Entry returns the entry address of the function.
func (f *Func) FileLine(pc uintptr) (file string, line int)
FileLine returns the file name and line number of the source code corresponding to the program counter pc. The result will not be accurate if pc is not a program counter within f.
func (f *Func) Name() string
Name returns the name of the function.
A MemProfileRecord describes the live objects allocated by a particular call sequence (stack trace).
type MemProfileRecord struct {
AllocBytes, FreeBytes int64 // number of bytes allocated, freed
AllocObjects, FreeObjects int64 // number of objects allocated, freed
Stack0 [32]uintptr // stack trace for this record; ends at first 0 entry
}
func (r *MemProfileRecord) InUseBytes() int64
InUseBytes returns the number of bytes in use (AllocBytes - FreeBytes).
func (r *MemProfileRecord) InUseObjects() int64
InUseObjects returns the number of objects in use (AllocObjects - FreeObjects).
func (r *MemProfileRecord) Stack() []uintptr
Stack returns the stack trace associated with the record, a prefix of r.Stack0.
A MemStats records statistics about the memory allocator.
type MemStats struct {
// Alloc is bytes of allocated heap objects.
//
// This is the same as HeapAlloc (see below).
Alloc uint64
// TotalAlloc is cumulative bytes allocated for heap objects.
//
// TotalAlloc increases as heap objects are allocated, but
// unlike Alloc and HeapAlloc, it does not decrease when
// objects are freed.
TotalAlloc uint64
// Sys is the total bytes of memory obtained from the OS.
//
// Sys is the sum of the XSys fields below. Sys measures the
// virtual address space reserved by the Go runtime for the
// heap, stacks, and other internal data structures. It's
// likely that not all of the virtual address space is backed
// by physical memory at any given moment, though in general
// it all was at some point.
Sys uint64
// Lookups is the number of pointer lookups performed by the
// runtime.
//
// This is primarily useful for debugging runtime internals.
Lookups uint64
// Mallocs is the cumulative count of heap objects allocated.
// The number of live objects is Mallocs - Frees.
Mallocs uint64
// Frees is the cumulative count of heap objects freed.
Frees uint64
// HeapAlloc is bytes of allocated heap objects.
//
// "Allocated" heap objects include all reachable objects, as
// well as unreachable objects that the garbage collector has
// not yet freed. Specifically, HeapAlloc increases as heap
// objects are allocated and decreases as the heap is swept
// and unreachable objects are freed. Sweeping occurs
// incrementally between GC cycles, so these two processes
// occur simultaneously, and as a result HeapAlloc tends to
// change smoothly (in contrast with the sawtooth that is
// typical of stop-the-world garbage collectors).
HeapAlloc uint64
// HeapSys is bytes of heap memory obtained from the OS.
//
// HeapSys measures the amount of virtual address space
// reserved for the heap. This includes virtual address space
// that has been reserved but not yet used, which consumes no
// physical memory, but tends to be small, as well as virtual
// address space for which the physical memory has been
// returned to the OS after it became unused (see HeapReleased
// for a measure of the latter).
//
// HeapSys estimates the largest size the heap has had.
HeapSys uint64
// HeapIdle is bytes in idle (unused) spans.
//
// Idle spans have no objects in them. These spans could be
// (and may already have been) returned to the OS, or they can
// be reused for heap allocations, or they can be reused as
// stack memory.
//
// HeapIdle minus HeapReleased estimates the amount of memory
// that could be returned to the OS, but is being retained by
// the runtime so it can grow the heap without requesting more
// memory from the OS. If this difference is significantly
// larger than the heap size, it indicates there was a recent
// transient spike in live heap size.
HeapIdle uint64
// HeapInuse is bytes in in-use spans.
//
// In-use spans have at least one object in them. These spans
// can only be used for other objects of roughly the same
// size.
//
// HeapInuse minus HeapAlloc esimates the amount of memory
// that has been dedicated to particular size classes, but is
// not currently being used. This is an upper bound on
// fragmentation, but in general this memory can be reused
// efficiently.
HeapInuse uint64
// HeapReleased is bytes of physical memory returned to the OS.
//
// This counts heap memory from idle spans that was returned
// to the OS and has not yet been reacquired for the heap.
HeapReleased uint64
// HeapObjects is the number of allocated heap objects.
//
// Like HeapAlloc, this increases as objects are allocated and
// decreases as the heap is swept and unreachable objects are
// freed.
HeapObjects uint64
// StackInuse is bytes in stack spans.
//
// In-use stack spans have at least one stack in them. These
// spans can only be used for other stacks of the same size.
//
// There is no StackIdle because unused stack spans are
// returned to the heap (and hence counted toward HeapIdle).
StackInuse uint64
// StackSys is bytes of stack memory obtained from the OS.
//
// StackSys is StackInuse, plus any memory obtained directly
// from the OS for OS thread stacks (which should be minimal).
StackSys uint64
// MSpanInuse is bytes of allocated mspan structures.
MSpanInuse uint64
// MSpanSys is bytes of memory obtained from the OS for mspan
// structures.
MSpanSys uint64
// MCacheInuse is bytes of allocated mcache structures.
MCacheInuse uint64
// MCacheSys is bytes of memory obtained from the OS for
// mcache structures.
MCacheSys uint64
// BuckHashSys is bytes of memory in profiling bucket hash tables.
BuckHashSys uint64
// GCSys is bytes of memory in garbage collection metadata.
GCSys uint64
// OtherSys is bytes of memory in miscellaneous off-heap
// runtime allocations.
OtherSys uint64
// NextGC is the target heap size of the next GC cycle.
//
// The garbage collector's goal is to keep HeapAlloc ≤ NextGC.
// At the end of each GC cycle, the target for the next cycle
// is computed based on the amount of reachable data and the
// value of GOGC.
NextGC uint64
// LastGC is the time the last garbage collection finished, as
// nanoseconds since 1970 (the UNIX epoch).
LastGC uint64
// PauseTotalNs is the cumulative nanoseconds in GC
// stop-the-world pauses since the program started.
//
// During a stop-the-world pause, all goroutines are paused
// and only the garbage collector can run.
PauseTotalNs uint64
// PauseNs is a circular buffer of recent GC stop-the-world
// pause times in nanoseconds.
//
// The most recent pause is at PauseNs[(NumGC+255)%256]. In
// general, PauseNs[N%256] records the time paused in the most
// recent N%256th GC cycle. There may be multiple pauses per
// GC cycle; this is the sum of all pauses during a cycle.
PauseNs [256]uint64
// PauseEnd is a circular buffer of recent GC pause end times,
// as nanoseconds since 1970 (the UNIX epoch).
//
// This buffer is filled the same way as PauseNs. There may be
// multiple pauses per GC cycle; this records the end of the
// last pause in a cycle.
PauseEnd [256]uint64
// NumGC is the number of completed GC cycles.
NumGC uint32
// NumForcedGC is the number of GC cycles that were forced by
// the application calling the GC function.
NumForcedGC uint32
// GCCPUFraction is the fraction of this program's available
// CPU time used by the GC since the program started.
//
// GCCPUFraction is expressed as a number between 0 and 1,
// where 0 means GC has consumed none of this program's CPU. A
// program's available CPU time is defined as the integral of
// GOMAXPROCS since the program started. That is, if
// GOMAXPROCS is 2 and a program has been running for 10
// seconds, its "available CPU" is 20 seconds. GCCPUFraction
// does not include CPU time used for write barrier activity.
//
// This is the same as the fraction of CPU reported by
// GODEBUG=gctrace=1.
GCCPUFraction float64
// EnableGC indicates that GC is enabled. It is always true,
// even if GOGC=off.
EnableGC bool
// DebugGC is currently unused.
DebugGC bool
// BySize reports per-size class allocation statistics.
//
// BySize[N] gives statistics for allocations of size S where
// BySize[N-1].Size < S ≤ BySize[N].Size.
//
// This does not report allocations larger than BySize[60].Size.
BySize [61]struct {
// Size is the maximum byte size of an object in this
// size class.
Size uint32
// Mallocs is the cumulative count of heap objects
// allocated in this size class. The cumulative bytes
// of allocation is Size*Mallocs. The number of live
// objects in this size class is Mallocs - Frees.
Mallocs uint64
// Frees is the cumulative count of heap objects freed
// in this size class.
Frees uint64
}
}
A StackRecord describes a single execution stack.
type StackRecord struct {
Stack0 [32]uintptr // stack trace for this record; ends at first 0 entry
}
func (r *StackRecord) Stack() []uintptr
Stack returns the stack trace associated with the record, a prefix of r.Stack0.
A TypeAssertionError explains a failed type assertion.
type TypeAssertionError struct {
// contains filtered or unexported fields
}
func (e *TypeAssertionError) Error() string
func (*TypeAssertionError) RuntimeError()
| Name | Synopsis |
|---|---|
| .. | |
| cgo | Package cgo contains runtime support for code generated by the cgo tool. |
| debug | Package debug contains facilities for programs to debug themselves while they are running. |
| msan | |
| pprof | Package pprof writes runtime profiling data in the format expected by the pprof visualization tool. |
| race | Package race implements data race detection logic. |
| trace | Go execution tracer. |