JEP 349: JFR Event Streaming (sandbox preview)
Chihiro Ito
chihiro.ito at oracle.com
Mon May 20 17:41:53 UTC 2019
Hi Erik,
I tried JFR Streaming with the following code [1], but occasionally an
exception occurred [2].
This is because the repository has not yet been created when JFR
Streaming reads the JFR file.
I made a patch as attached.
How do I handle bug reports? Should I raise the issue as usual?
[1]
public static void premain(String args, Instrumentation inst) {
RecordingStream r = new RecordingStream();
r.startAsync();
Runtime.getRuntime().addShutdownHook(new Thread() {
public void run() {
r.close();
}
});
}
public static void main(String... args) throws Exception {
TimeUnit.SECONDS.sleep(2);
System.out.println("Completed");
}
[2]
java.nio.file.NoSuchFileException: /tmp/2019_05_20_00_30_44_445
at
java.base/sun.nio.fs.UnixException.translateToIOException(UnixException.java:92)
at
java.base/sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:111)
at
java.base/sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:116)
at
java.base/sun.nio.fs.UnixFileSystemProvider.newDirectoryStream(UnixFileSystemProvider.java:432)
at java.base/java.nio.file.Files.newDirectoryStream(Files.java:542)
at
jdk.jfr/jdk.jfr.consumer.EventSetLocation.updateEventSets(EventSetLocation.java:129)
at
jdk.jfr/jdk.jfr.consumer.EventSetLocation.acquire(EventSetLocation.java:108)
at jdk.jfr/jdk.jfr.consumer.EventSet.next(EventSet.java:210)
at jdk.jfr/jdk.jfr.consumer.EventRunner.process(EventRunner.java:132)
at jdk.jfr/jdk.jfr.consumer.EventRunner.execute(EventRunner.java:105)
at
jdk.jfr/jdk.jfr.consumer.EventRunner.lambda$run$0(EventRunner.java:89)
at jdk.jfr/jdk.jfr.consumer.EventRunner$1.run(EventRunner.java:96)
at jdk.jfr/jdk.jfr.consumer.EventRunner$1.run(EventRunner.java:93)
at
java.base/java.security.AccessController.doPrivileged(AccessController.java:391)
at
jdk.jfr/jdk.jfr.consumer.EventRunner.doPriviliged(EventRunner.java:93)
at jdk.jfr/jdk.jfr.consumer.EventRunner.run(EventRunner.java:89)
at java.base/java.lang.Thread.run(Thread.java:830)
Regards,
Chihiro
On 2019/05/18 1:27, Erik Gahlin wrote:
> Hi folks,
>
> We have created a sandbox for JEP 349: JFR Event Streaming[1] for
> people who
> like to try the feature out. It is work in progress, but plan is to
> integrate it
> in the next couple of months, but not for JDK 13.
>
> A build can be created like this:
>
> $ hg clone -b JEP-349-branch -r 53dccc90a5be
> http://hg.openjdk.java.net/jdk/sandbox jep-349
> $ cd jep-349
> $ bash configure
> $ make images
> $ ./build/*/images/jdk/bin/java -version
>
> See [2] and [3] for more information on how to use the sandbox
> repository and
> build the JDK.
>
> For testing purposes, and to illustrate how the Event Streaming API
> can be
> used, there exists a Java agent[4] that aggregates event data and
> print the
> results on standard out.
>
> Example,
> http://cr.openjdk.java.net/~egahlin/health-report-agent/health-report-example.txt
>
> =================== HEALTH REPORT === 2019-05-16 23:57:50
> ====================
> | GC: G1Old/G1New Phys. memory: 28669 MB Alloc Rate: 8
> MB/s |
> | OC Count : 28 Initial Heap: 448 MB Total Alloc: 190
> MB |
> | OC Pause Avg: 40.1 ms Used Heap : 19 MB Thread Count:
> 20.0 |
> | OC Pause Max: 48.8 ms Commit. Heap: 47 MB Class Count :
> 3894.0 |
> | YC Count : 8 CPU Machine : 20.12 % Safepoints:
> 335 |
> | YC Pause Avg: 5.7 ms CPU JVM User : 10.28 % Max Safepoint:
> 46.4 ms |
> | YC Pause Max: 22.4 ms CPU JVM System: 1.07 % Max Comp. Time:
> 728.3 ms |
> |--- Top Allocation Methods -------------------------------
> -----------------|
> | DataBufferInt.<init>(int) 11.27 % |
> | Component.size() 9.01 % |
> | BufferedContext.validate(...) 6.21 % |
> | Path2D$Double.<init>(...) 5.87 % |
> | SunGraphics2D.clone() 5.85 % |
> |--- Hot Methods
> ------------------------------------------------------------|
> | DRenderer._endRendering(int, int)
> 51.11 % |
> | DRenderer.copyAARow(...) 6.67 % |
> | Arrays.fill(...) 4.44 % |
> | StringConcatFactory.doStringConcat(...) 2.22 % |
> | MarlinTileGenerator.getAlphaNoRLE(...) 2.22 % |
> ==============================================================================
>
>
> The agent can be started like this:
>
> $ java -javaagent:health-report.jar MyApp
>
> The interval at which events are flushed can be changed with the interval
> option. The default interval is 1 second. For example, to flush
> every ten second, use -javaagent:health-report.jar=interval=10
>
> For quick experimentation, the agent can also be run as a Java program
> that
> allocate objects in a loop.
>
> $ java Main.java
>
> Two new classes, EventStream[5] and RecordingStream[6], have been
> added to the
> jdk.jfr.consumer package. A EventFilter class may be added later for more
> advanced filtering.
>
> The JVM implementation is close to finished, but there is work on the
> consumer
> side left. There is also an effort to reduce allocation on the client.
>
> To get started without using the agent, the CPU load can be printed
> like this:
>
> Configuration c = Configuration.getConfiguration("default");
> try (RecordingStream r = new RecordingStream(c)) {
> r.onEvent("jdk.CPULoad", event -> {
> float percentage = 100 * event.getFloat("machineTotal");
> System.out.printf("CPU: %.2f %% \n\n", percentage);
> });
> r.start();
> }
>
> Feedback is very much welcomed!
>
> Thanks
> Erik and Markus
>
> Outages, known issues and limitations
> -------------------------------------
>
> - Only start/open one RecordingStream at a time
> Implementation has not been tested with two RecordingStreams
> simultaneously.
>
> - Exception handling
> Behavior is undefined if an exception is thrown in a handler.
>
> - Parser level filtering disabled
> Purpose of parser level filtering is to be able to use predefined
> configurations, for example default.jfc, but only pay the overhead in the
> parser of the events that the stream is listening to. Now all events are
> parsed. Workaround is to only enable the events of interest.
>
> - Chunk files not removed
> Chunk files may be left behind in the disk repository when the JVM exits.
>
> - EventStream::openFile(...)
> Not possible to open a file as an event stream.
>
> - EventStream:::openRepository(...)
> Not possible to open a (remote) directory as an event stream.
>
> - EventStream.setReuse(...) (cursor mode)
> Method has not been added / implemented.
>
> - EventStream.setParallel(...)
> Method has not been added / implemented as it will make most sense if
> EventStream::openFile exists.
>
> - EventStream.setOrdered(...)
> Method has not been added. Need to figure out how to handle events
> that arrives
> way out of order. For example,
>
> MyEvent event = new MyEvent();
> event.begin();
> event.end(); // end timestamp taken here
> Thread.sleep(1000_000);
> event.commit();
>
> Currently a best effort is made to deliver events in order.
>
> [1] https://openjdk.java.net/jeps/349
> [2] http://cr.openjdk.java.net/~chegar/docs/sandbox.html
> [3] http://hg.openjdk.java.net/jdk/jdk/raw-file/tip/doc/building.html
> [4] http://cr.openjdk.java.net/~egahlin/health-report-agent/
> [5]
> http://cr.openjdk.java.net/~egahlin/jep-349-preview/docs/jdk/jfr/consumer/RecordingStream.html
> [6]
> http://cr.openjdk.java.net/~egahlin/jep-349-preview/docs/jdk/jfr/consumer/EventStream.html
>
>
-------------- next part --------------
diff --git a/src/jdk.jfr/share/classes/jdk/jfr/consumer/EventSetLocation.java b/src/jdk.jfr/share/classes/jdk/jfr/consumer/EventSetLocation.java
--- a/src/jdk.jfr/share/classes/jdk/jfr/consumer/EventSetLocation.java
+++ b/src/jdk.jfr/share/classes/jdk/jfr/consumer/EventSetLocation.java
@@ -126,14 +126,19 @@
private void updateEventSets(EventSet previousEventSet) throws IOException {
List<Path> added = new ArrayList<>();
Set<Path> current = new HashSet<>();
- try (DirectoryStream<Path> dirStream = Files.newDirectoryStream(path, "*.jfr")) {
- for (Path p : dirStream) {
- if (!lastPaths.containsKey(p)) {
- added.add(p);
- Logger.log(LogTag.JFR_SYSTEM_STREAMING, LogLevel.DEBUG, "New file found: " + p.toAbsolutePath());
+ if(Files.exists(path)) {
+ Logger.log(LogTag.JFR_SYSTEM_STREAMING, LogLevel.DEBUG, "Repository found: " + path.toAbsolutePath());
+ try (DirectoryStream<Path> dirStream = Files.newDirectoryStream(path, "*.jfr")) {
+ for (Path p : dirStream) {
+ if (!lastPaths.containsKey(p)) {
+ added.add(p);
+ Logger.log(LogTag.JFR_SYSTEM_STREAMING, LogLevel.DEBUG, "New file found: " + p.toAbsolutePath());
+ }
+ current.add(p);
}
- current.add(p);
}
+ } else {
+ Logger.log(LogTag.JFR_SYSTEM_STREAMING, LogLevel.DEBUG, "Repository does not found: " + path.toAbsolutePath());
}
List<Path> removed = new ArrayList<>();
for (Path p : lastPaths.keySet()) {
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