Documentation
¶
Index ¶
Constants ¶
const EventAlloc = "alloc"
const EventCPU = "cpu"
const EventLock = "lock"
const (
// EventPark is a thread parked, as by LockSupport.park.
EventPark = "park"
)
The events a profile's samples are of.
const EventWall = "wall"
const UnitBytes = "bytes"
const (
UnitNanos = "ns"
)
The units a sample's Value is in.
const UnitSamples = "samples"
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type DecodeOptions ¶
type DecodeOptions struct {
// After is the watermark: only events that end after it are decoded, so
// a dump of the whole recording so far yields only what it added.
After time.Time
// Threads splits each stack's samples by the thread they were taken on.
Threads bool
// MaxStackDepth keeps only the leaf-most frames of deeper stacks; zero
// keeps every frame.
MaxStackDepth int
}
DecodeOptions say which of a recording's events Decode keeps and how it aggregates them.
type Profile ¶
type Profile struct {
Samples []StackSample
Counts map[string]int64
// From and Latest are the earliest and latest end of the events decoded;
// both are zero when no event ended after DecodeOptions.After.
From, Latest time.Time
}
Profile is what Decode read from a recording: a Sample per event, thread (when split by thread) and stack, the samples of each event, and the window of the events it decoded.
func Decode ¶
func Decode(data []byte, options DecodeOptions) (profile Profile, err error)
Decode reads the profiling events of a JFR recording, as the JDK's Flight Recorder or async-profiler writes it, one or more chunks long: execution and wall-clock samples, allocations, monitor waits and parks. It refuses an empty or malformed recording, and a stack, frame or thread its chunk's constant pool does not hold.
type StackSample ¶
type StackSample struct {
// Timestamp is the end of the dump's window: the latest event it added.
Timestamp time.Time `json:"timestamp" pretty:"label=At" sort:"timestamp"`
// From is the start of the dump's window: the earliest event it added.
From time.Time `json:"from" pretty:"hide"`
Event string `json:"event" filter:"terms"`
Thread string `json:"thread,omitempty" filter:"terms"`
// Frame is the stack's leaf, the frame the event happened in.
Frame string `json:"frame" pretty:"label=Top frame" filter:"text"`
// Stack is the collapsed stack, root first: frames joined by ";", headed
// by "[truncated]" when the recorder or MaxStackDepth cut its root side.
Stack string `json:"stack" pretty:"hide" filter:"text"`
Samples int64 `json:"samples" sort:"samples"`
// Value is the samples' weight in Unit: their count for cpu and wall,
// the bytes allocated for alloc, the time blocked for lock and park.
Value int64 `json:"value" sort:"value"`
Unit string `json:"unit"`
}
StackSample is one stack's share of a dump: the samples of one event that ended on that stack, on one thread when a capture splits them by thread, within the window a dump added to the recording.
Source Files