@Retention(RUNTIME) @Inherited @Target(TYPE) public @interface Period
The following example shows how the Period
annotation can be used to emit events at different intervals.
@Period("1 s")
@Name("Counter")
class CountEvent extends Event {
int count;
}
@Period("3 s")
@Name("Fizz")
class FizzEvent extends Event {
}
@Period("5 s")
@Name("Buzz")
class BuzzEvent extends Event {
}
var counter = new AtomicInteger();
FlightRecorder.addPeriodicEvent(CountEvent.class, () -> {
CountEvent event = new CountEvent();
event.count = counter.incrementAndGet();
event.commit();
});
FlightRecorder.addPeriodicEvent(FizzEvent.class, () -> {
new FizzEvent().commit();
});
FlightRecorder.addPeriodicEvent(BuzzEvent.class, () -> {
new BuzzEvent().commit();
});
var sb = new StringBuilder();
var last = new AtomicInteger();
var current = new AtomicInteger();
try (var r = new RecordingStream()) {
r.onEvent("Counter", e -> current.set(e.getValue("count")));
r.onEvent("Fizz", e -> sb.append("Fizz"));
r.onEvent("Buzz", e -> sb.append("Buzz"));
r.onFlush(() -> {
if (current.get() != last.get()) {
System.out.println(sb.isEmpty() ? current : sb);
last.set(current.get());
sb.setLength(0);
}
});
r.start();
}
Modifier and Type | Optional Element | Description |
---|---|---|
String |
value |
Returns the default setting value for a periodic setting. |
Modifier and Type | Field | Description |
---|---|---|
static final String |
NAME |
Settings name "period" for configuring periodic events |
static final String NAME
"period"
for configuring periodic eventsString value
String representation of a positive Long
value followed by an empty space and one of the following units:
"ns"
(nanoseconds)
"us"
(microseconds)
"ms"
(milliseconds)
"s"
(seconds)
"m"
(minutes)
"h"
(hours)
"d"
(days)
Example values: "0 ns"
, "10 ms"
, and "1 s"
.
A period may also be "everyChunk"
to specify that it occurs at least once for every recording file. The number of events that are emitted depends on how many times the file rotations occur when data is recorded.
null
"everyChunk"
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Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
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https://docs.oracle.com/en/java/javase/21/docs/api/jdk.jfr/jdk/jfr/Period.html