com.papertrail.profiler

Class CpuProfile

java.lang.Object

com.papertrail.profiler.CpuProfile

public class CpuProfile
extends Object

A CPU profile.

Field Summary

Fields

Modifier and Type	Field and Description
long	m_count
Duration	m_duration
long	m_missed

Constructor Summary

Constructors

Constructor and Description
CpuProfile(Map<List<StackTraceElement>,Long> counts, Duration duration, long count, long missed)

Method Summary

Modifier and Type	Method and Description
protected static boolean	isRunnable(StackTraceElement elem) When looking for RUNNABLEs, the JVM's notion of runnable differs from the from kernel's definition and for some well known cases, we can filter out threads that are actually asleep.
static String	mainClassName() Get the main class name for the currently running application.
CpuProfile	record(Duration howlong, int frequency)
static CpuProfile	record(Duration howlong, int frequency, Thread.State state) Profile CPU usage of threads in `state` for `howlong`, sampling stacks at `frequency` Hz.
static Future<CpuProfile>	recordInThread(Duration howlong, int frequency)
static Future<CpuProfile>	recordInThread(Duration howlong, int frequency, Thread.State state) Call `record` in a thread with the given parameters, returning a `Future` representing the completion of the profile.
void	writeGoogleProfile(OutputStream out) Write a Google pprof-compatible profile to `out`.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

m_duration

public final Duration m_duration

m_count

public final long m_count

m_missed

public final long m_missed

Constructor Detail

CpuProfile

public CpuProfile(Map<List<StackTraceElement>,Long> counts,
                  Duration duration,
                  long count,
                  long missed)

Method Detail

writeGoogleProfile

public void writeGoogleProfile(OutputStream out)
                        throws IOException

Write a Google pprof-compatible profile to `out`. The format is documented here: http://google-perftools.googlecode.com/svn/trunk/doc/cpuprofile-fileformat.html

Parameters:

out - And OutputStream to which the pprof output will be written

Throws:

IOException - if any operation on the OutputStream fails

isRunnable

protected static boolean isRunnable(StackTraceElement elem)

When looking for RUNNABLEs, the JVM's notion of runnable differs from the from kernel's definition and for some well known cases, we can filter out threads that are actually asleep. See http://www.brendangregg.com/blog/2014-06-09/java-cpu-sampling-using-hprof.html

Parameters:

elem - StackTraceElement to check

Returns:

true if it's not a known idle method

record

public static CpuProfile record(Duration howlong,
                                int frequency,
                                Thread.State state)

Profile CPU usage of threads in `state` for `howlong`, sampling stacks at `frequency` Hz. As an example, using Nyquist's sampling theorem, we see that sampling at 100Hz will accurately represent components 50Hz or less; ie. any stack that contributes 2% or more to the total CPU time. Note that the maximum sampling frequency is set to 1000Hz. Anything greater than this is likely to consume considerable amounts of CPU while sampling. The profiler will discount its own stacks. TODO: - Should we synthesize GC frames? GC has significant runtime impact, so it seems nonfaithful to exlude them. - Limit stack depth?

Parameters:

howlong - Duration of profile

frequency - polling interval

state - Thread.State to match against

Returns:

CpuProfile results

record

public CpuProfile record(Duration howlong,
                         int frequency)

recordInThread

public static Future<CpuProfile> recordInThread(Duration howlong,
                                                int frequency,
                                                Thread.State state)

Call `record` in a thread with the given parameters, returning a `Future` representing the completion of the profile.

Parameters:

howlong - Duration of profile

frequency - polling interval

state - Thread.State to match against

Returns:

Future containing CpuProfile results

recordInThread

public static Future<CpuProfile> recordInThread(Duration howlong,
                                                int frequency)

mainClassName

public static String mainClassName()

Get the main class name for the currently running application. Note that this works only by heuristic, and may not be accurate. TODO: take into account the standard callstack around scala invocations better.

Returns:

main class name