Module jdk.jfr
Package jdk.jfr.consumer
package jdk.jfr.consumer
This package contains classes for consuming Flight Recorder data.
In the following example, the program prints a histogram of all method samples in a recording.
public static void main(String[] args) throws IOException {
if (args.length != 1) {
System.err.println("Must specify a recording file.");
return;
}
RecordingFile.readAllEvents(Path.of(args[0])).stream()
.filter(e -> e.getEventType().getName().equals("jdk.ExecutionSample"))
.map(e -> e.getStackTrace())
.filter(s -> s != null)
.map(s -> s.getFrames().get(0))
.filter(f -> f.isJavaFrame())
.map(f -> f.getMethod())
.collect(
Collectors.groupingBy(m -> m.getType().getName() + "." + m.getName() + " " + m.getDescriptor(),
Collectors.counting()))
.entrySet()
.stream()
.sorted((a, b) -> b.getValue().compareTo(a.getValue()))
.forEach(e -> System.out.printf("%8d %s\n", e.getValue(), e.getKey()));
}
Null-handling
All methods define whether they accept or return null
in the Javadoc.
Typically this is expressed as "not null"
. If a null
parameter is used where it is not allowed, a
java.lang.NullPointerException
is thrown. If a null
parameters is passed to a method that throws other exceptions, such as
java.io.IOException
, the java.lang.NullPointerException
takes
precedence, unless the Javadoc for the method explicitly states how
null
is handled, i.e. by throwing java.lang.IllegalArgumentException
.
- Since:
- 9
-
ClassDescriptionRepresents a stream of events.Event that contains information about event types and configurations.A recorded Java type, such as a class or an interface.A recorded Java class loader.A recorded event.A recorded frame in a stack trace.A recorded method.A complex data type that consists of one or more fields.A recorded stack trace.A recorded thread.A recorded Java thread group.A recording file.A recording stream produces events from the current JVM (Java Virtual Machine).