const Compiler = "gc"
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 GOARCH string = sys.TheGoarch
GOARCH is the running program's architecture target: 386, amd64, or arm.
const GOOS string = sys.TheGoos
GOOS is the running program's operating system target: one of darwin, freebsd, linux, and so on.
var MemProfileRate int = 512 * 1024
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).
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 return the file and line number of the instruction immediately following the call. To look up the file and line number of the call itself, use pc[i]-1. As an exception to this rule, if pc[i-1] corresponds to the function runtime.sigpanic, then pc[i] is the program counter of a faulting instruction and should be used without any subtraction.
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 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 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.
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 SetFinalizer(obj interface{}, finalizer interface{})
SetFinalizer sets the finalizer associated with x to f. When the garbage collector finds an unreachable block with an associated finalizer, it clears the association and runs f(x) in a separate goroutine. This makes x reachable again, but now without an associated finalizer. Assuming that SetFinalizer is not called again, the next time the garbage collector sees that x is unreachable, it will free x.
SetFinalizer(x, nil) clears any finalizer associated with x.
The argument x must be a pointer to an object allocated by calling new or by taking the address of a composite literal. The argument f must be a function that takes a single argument to which x's type can be assigned, and can have arbitrary ignored return values. If either of these is not true, SetFinalizer aborts 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 x is scheduled to run at some arbitrary time after x 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 *x 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 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 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".
type BlockProfileRecord struct {
Count int64
Cycles int64
StackRecord
}
BlockProfileRecord describes blocking events originated at a particular call sequence (stack trace).
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()
}
The Error interface identifies a run time error.
type Func struct {
// contains filtered or unexported fields
}
A Func represents a Go function in the running binary.
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.
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
}
A MemProfileRecord describes the live objects allocated by a particular call sequence (stack trace).
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.
type MemStats struct {
// General statistics.
Alloc uint64 // bytes allocated and not yet freed
TotalAlloc uint64 // bytes allocated (even if freed)
Sys uint64 // bytes obtained from system (sum of XxxSys below)
Lookups uint64 // number of pointer lookups
Mallocs uint64 // number of mallocs
Frees uint64 // number of frees
// Main allocation heap statistics.
HeapAlloc uint64 // bytes allocated and not yet freed (same as Alloc above)
HeapSys uint64 // bytes obtained from system
HeapIdle uint64 // bytes in idle spans
HeapInuse uint64 // bytes in non-idle span
HeapReleased uint64 // bytes released to the OS
HeapObjects uint64 // total number of allocated objects
// Low-level fixed-size structure allocator statistics.
// Inuse is bytes used now.
// Sys is bytes obtained from system.
StackInuse uint64 // bytes used by stack allocator
StackSys uint64
MSpanInuse uint64 // mspan structures
MSpanSys uint64
MCacheInuse uint64 // mcache structures
MCacheSys uint64
BuckHashSys uint64 // profiling bucket hash table
GCSys uint64 // GC metadata
OtherSys uint64 // other system allocations
// Garbage collector statistics.
NextGC uint64 // next collection will happen when HeapAlloc ≥ this amount
LastGC uint64 // end time of last collection (nanoseconds since 1970)
PauseTotalNs uint64
PauseNs [256]uint64 // circular buffer of recent GC pause durations, most recent at [(NumGC+255)%256]
PauseEnd [256]uint64 // circular buffer of recent GC pause end times
NumGC uint32
GCCPUFraction float64 // fraction of CPU time used by GC
EnableGC bool
DebugGC bool
// Per-size allocation statistics.
// 61 is NumSizeClasses in the C code.
BySize [61]struct {
Size uint32
Mallocs uint64
Frees uint64
}
}
A MemStats records statistics about the memory allocator.
type StackRecord struct {
Stack0 [32]uintptr // stack trace for this record; ends at first 0 entry
}
A StackRecord describes a single execution stack.
func (r *StackRecord) Stack() []uintptr
Stack returns the stack trace associated with the record, a prefix of r.Stack0.
type TypeAssertionError struct {
// contains filtered or unexported fields
}
A TypeAssertionError explains a failed type assertion.
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. |