Module jdk.management.jfr
Package jdk.management.jfr

Class RemoteRecordingStream

java.lang.Object
jdk.management.jfr.RemoteRecordingStream
All Implemented Interfaces:
AutoCloseable, EventStream
public final class RemoteRecordingStream extends Object implements EventStream
An implementation of an EventStream that can serialize events over the network using an MBeanServerConnection.

The following example shows how to record garbage collection pauses and CPU usage on a remote host and print the events to standard out. 

     
     String host = "com.example";
     int port = 4711;

     String url = "service:jmx:rmi:///jndi/rmi://" + host + ":" + port + "/jmxrmi";

     JMXServiceURL u = new JMXServiceURL(url);
     JMXConnector c = JMXConnectorFactory.connect(u);
     MBeanServerConnection conn = c.getMBeanServerConnection();

     try (var rs = new RemoteRecordingStream(conn)) {
         rs.enable("jdk.GCPhasePause").withoutThreshold();
         rs.enable("jdk.CPULoad").withPeriod(Duration.ofSeconds(1));
         rs.onEvent("jdk.CPULoad", System.out::println);
         rs.onEvent("jdk.GCPhasePause", System.out::println);
         rs.start();
     }
Since:
16

  • Constructor Details

    • RemoteRecordingStream

      public RemoteRecordingStream(MBeanServerConnection connection) throws IOException
      Creates an event stream that operates against a MBeanServerConnection that has a registered FlightRecorderMXBean.

      To configure event settings, use setSettings(Map).

      Parameters:
      connection - the MBeanServerConnection where the FlightRecorderMXBean is registered, not null
      Throws:
      IOException - if a stream can't be opened, an I/O error occurs when trying to access the repository or the FlightRecorderMXBean
      SecurityException - if a security manager exists and its checkRead method denies read access to the directory, or files in the directory.

    • RemoteRecordingStream

      public RemoteRecordingStream(MBeanServerConnection connection, Path directory) throws IOException
      Creates an event stream that operates against a MBeanServerConnection that has a registered FlightRecorderMXBean.

      To configure event settings, use setSettings(Map).

      Parameters:
      connection - the MBeanServerConnection where the FlightRecorderMXBean is registered, not null
      directory - the directory to store event data that is downloaded, not null
      Throws:
      IOException - if a stream can't be opened, an I/O error occurs when trying to access the repository or the FlightRecorderMXBean
      SecurityException - if a security manager exists and its checkRead method denies read access to the directory, or files in the directory.

  • Method Details

    • setSettings

      public void setSettings(Map<String,String> settings)
      Replaces all settings for this recording stream.

      The following example connects to a remote host and stream events using settings from the "default" configuration. 

       {
     

     String host = "com.example";
     int port = 4711;

     String url = "service:jmx:rmi:///jndi/rmi://" + host + ":" + port + "/jmxrmi";

     JMXServiceURL u = new JMXServiceURL(url);
     JMXConnector c = JMXConnectorFactory.connect(u);
     MBeanServerConnection conn = c.getMBeanServerConnection();

     try (final var rs = new RemoteRecordingStream(conn)) {
         rs.onMetadata(e -> {
             for (Configuration c : e.getConfigurations()) {
                 if (c.getName().equals("default")) {
                     rs.setSettings(c.getSettings());
                 }
             }
         });
         rs.onEvent(System.out::println);
         rs.start();
     }
      Parameters:
      settings - the settings to set, not null
      See Also:

    • disable

      public EventSettings disable(String name)
      Disables event with the specified name.

      If multiple events with same name (for example, the same class is loaded in different class loaders), then all events that match the name are disabled.

      Parameters:
      name - the settings for the event, not null
      Returns:
      an event setting for further configuration, not null

    • enable

      public EventSettings enable(String name)
      Enables the event with the specified name.

      If multiple events have the same name (for example, the same class is loaded in different class loaders), then all events that match the name are enabled.

      Parameters:
      name - the settings for the event, not null
      Returns:
      an event setting for further configuration, not null
      See Also:

    • setMaxAge

      public void setMaxAge(Duration maxAge)
      Determines how far back data is kept for the stream.

      To control the amount of recording data stored on disk, the maximum length of time to retain the data can be specified. Data stored on disk that is older than the specified length of time is removed by the Java Virtual Machine (JVM).

      If neither maximum limit or the maximum age is set, the size of the recording may grow indefinitely if events are not consumed.

      Parameters:
      maxAge - the length of time that data is kept, or null if infinite
      Throws:
      IllegalArgumentException - if maxAge is negative
      IllegalStateException - if the recording is in the CLOSED state

    • setMaxSize

      public void setMaxSize(long maxSize)
      Determines how much data is kept for the stream.

      To control the amount of recording data that is stored on disk, the maximum amount of data to retain can be specified. When the maximum limit is exceeded, the Java Virtual Machine (JVM) removes the oldest chunk to make room for a more recent chunk.

      If neither maximum limit or the maximum age is set, the size of the recording may grow indefinitely if events are not consumed.

      The size is measured in bytes.

      Parameters:
      maxSize - the amount of data to retain, 0 if infinite
      Throws:
      IllegalArgumentException - if maxSize is negative
      IllegalStateException - if the recording is in CLOSED state

    • onEvent

      public void onEvent(Consumer<RecordedEvent> action)
      Description copied from interface: EventStream
      Registers an action to perform on all events in the stream.

      To perform an action on a subset of event types, consider using EventStream.onEvent(String, Consumer) and EventStream.onMetadata(Consumer) as it is likely more performant than any selection or filtering mechanism implemented in a generic action.

      Specified by:
      onEvent in interface EventStream
      Parameters:
      action - an action to perform on each RecordedEvent, not null
      See Also:

    • onEvent

      public void onEvent(String eventName, Consumer<RecordedEvent> action)
      Description copied from interface: EventStream
      Registers an action to perform on all events matching a name.
      Specified by:
      onEvent in interface EventStream
      Parameters:
      eventName - the name of the event, not null
      action - an action to perform on each RecordedEvent matching the event name, not null

    • onFlush

      public void onFlush(Runnable action)
      Description copied from interface: EventStream
      Registers an action to perform after the stream has been flushed.
      Specified by:
      onFlush in interface EventStream
      Parameters:
      action - an action to perform after the stream has been flushed, not null

    • onError

      public void onError(Consumer<Throwable> action)
      Description copied from interface: EventStream
      Registers an action to perform if an exception occurs.

      If an action is not registered, an exception stack trace is printed to standard error.

      Registering an action overrides the default behavior. If multiple actions have been registered, they are performed in the order of registration.

      If this method itself throws an exception, resulting behavior is undefined.

      Specified by:
      onError in interface EventStream
      Parameters:
      action - an action to perform if an exception occurs, not null

    • onClose

      public void onClose(Runnable action)
      Description copied from interface: EventStream
      Registers an action to perform when the stream is closed.

      If the stream is already closed, the action will be performed immediately in the current thread.

      Specified by:
      onClose in interface EventStream
      Parameters:
      action - an action to perform after the stream is closed, not null
      See Also:

    • close

      public void close()
      Description copied from interface: EventStream
      Releases all resources associated with this stream.

      If a stream is started, asynchronously or synchronously, it is stopped immediately or after the next flush. This method does NOT guarantee that all registered actions are completed before return.

      Closing a previously closed stream has no effect.

      Specified by:
      close in interface AutoCloseable
      Specified by:
      close in interface EventStream

    • remove

      public boolean remove(Object action)
      Description copied from interface: EventStream
      Unregisters an action.

      If the action has been registered multiple times, all instances are unregistered.

      Specified by:
      remove in interface EventStream
      Parameters:
      action - the action to unregister, not null
      Returns:
      true if the action was unregistered, false otherwise
      See Also:

    • setReuse

      public void setReuse(boolean reuse)
      Description copied from interface: EventStream
      Specifies that the event object in an EventStream.onEvent(Consumer) action can be reused.

      If reuse is set to true, an action should not keep a reference to the event object after the action has completed.

      Specified by:
      setReuse in interface EventStream
      Parameters:
      reuse - true if an event object can be reused, false otherwise

    • setOrdered

      public void setOrdered(boolean ordered)
      Description copied from interface: EventStream
      Specifies that events arrives in chronological order, sorted by the time they were committed to the stream.
      Specified by:
      setOrdered in interface EventStream
      Parameters:
      ordered - if event objects arrive in chronological order to EventStream.onEvent(Consumer)

    • setStartTime

      public void setStartTime(Instant startTime)
      Description copied from interface: EventStream
      Specifies the start time of the stream.

      The start time must be set before starting the stream

      Specified by:
      setStartTime in interface EventStream
      Parameters:
      startTime - the start time, not null
      See Also:

    • setEndTime

      public void setEndTime(Instant endTime)
      Description copied from interface: EventStream
      Specifies the end time of the stream.

      The end time must be set before starting the stream.

      At end time, the stream is closed.

      Specified by:
      setEndTime in interface EventStream
      Parameters:
      endTime - the end time, not null
      See Also:

    • start

      public void start()
      Description copied from interface: EventStream
      Starts processing of actions.

      Actions are performed in the current thread.

      To stop the stream, use the EventStream.close() method.

      Specified by:
      start in interface EventStream

    • startAsync

      public void startAsync()
      Description copied from interface: EventStream
      Starts asynchronous processing of actions.

      Actions are performed in a single separate thread.

      To stop the stream, use the EventStream.close() method.

      Specified by:
      startAsync in interface EventStream

    • stop

      public boolean stop()
      Stops the recording stream.

      Stops a started stream and waits until all events in the recording have been consumed.

      Invoking this method in an action, for example in the onEvent(Consumer) method, could block the stream indefinitely. To stop the stream abruptly, use the close() method.

      The following code snippet illustrates how this method can be used in conjunction with the startAsync() method to monitor what happens during a test method: 

        AtomicLong bytesWritten = new AtomicLong();
  try (var r = new RemoteRecordingStream(connection)) {
    r.setMaxSize(Long.MAX_VALUE);
    r.enable("jdk.FileWrite").withoutThreshold();
    r.onEvent(event ->
      bytesWritten.addAndGet(event.getLong("bytesWritten"))
    );
    r.startAsync();
    testFoo();
    r.stop();
    if (bytesWritten.get() > 1_000_000L) {
      r.dump(Path.of("file-write-events.jfr"));
      throw new AssertionError("testFoo() writes too much data to disk");
    }
  }
      Returns:
      true if recording is stopped, false otherwise
      Throws:
      IllegalStateException - if the recording is not started or is already stopped
      Since:
      20

    • dump

      public void dump(Path destination) throws IOException
      Writes recording data to a file.

      The recording stream must be started, but not closed.

      It's highly recommended that a max age or max size is set before starting the stream. Otherwise, the dump may not contain any events.

      Parameters:
      destination - the location where recording data is written, not null
      Throws:
      IOException - if the recording data can't be copied to the specified location, or if the stream is closed, or not started.
      SecurityException - if a security manager exists and the caller doesn't have FilePermission to write to the destination path
      Since:
      17
      See Also:

    • awaitTermination

      public void awaitTermination(Duration timeout) throws InterruptedException
      Description copied from interface: EventStream
      Blocks until all actions are completed, or the stream is closed, or the timeout occurs, or the current thread is interrupted, whichever happens first.
      Specified by:
      awaitTermination in interface EventStream
      Parameters:
      timeout - the maximum time to wait, not null
      Throws:
      InterruptedException - if interrupted while waiting
      See Also:

    • awaitTermination

      public void awaitTermination() throws InterruptedException
      Description copied from interface: EventStream
      Blocks until all actions are completed, or the stream is closed, or the current thread is interrupted, whichever happens first.
      Specified by:
      awaitTermination in interface EventStream
      Throws:
      InterruptedException - if interrupted while waiting
      See Also: