Java profiling Do It Yourself

Java profiling
Do It Yourself
Alexey Ragozin
alexey.ragozin@gmail.com

JVM diagnostic interfaces
• JMX
• JVMTI – native API only
• Attach API
 Ad hoc instrumentation
 and more
• Perf counters
• Heap dump
• Flight recorder

MBeans: threading
 CPU usage per thread (user / sys)
 Memory allocation per thread
 Block / wait times
 Should be enabled
 Stack traces
Invaluable

SJK: ttop
2014-10-01T19:27:22.825+0400 Process summary
process cpu=101.80%
application cpu=100.50% (user=86.21% sys=14.29%)
other: cpu=1.30%
GC cpu=0.00% (young=0.00%, old=0.00%)
heap allocation rate 123mb/s
[000037] user=83.66% sys=14.02% alloc= 121mb/s - Proxy:ExtendTcpProxyService1:TcpAcceptor:TcpProcessor
[000075] user= 0.97% sys= 0.08% alloc= 411kb/s - RMI TCP Connection(35)-10.139.200.51
[000029] user= 0.61% sys=-0.00% alloc= 697kb/s - Invocation:Management
[000073] user= 0.49% sys=-0.01% alloc= 343kb/s - RMI TCP Connection(33)-10.128.46.114
[000023] user= 0.24% sys=-0.01% alloc= 10kb/s - PacketPublisher
[000022] user= 0.00% sys= 0.10% alloc= 11kb/s - PacketReceiver
[000026] user= 0.12% sys=-0.07% alloc= 2217b/s - Cluster|Member(Id=18, Timestamp=2014-10-01 15:58:3...
[000076] user= 0.00% sys= 0.04% alloc= 6657b/s - JMX server connection timeout 76
[000021] user= 0.00% sys= 0.03% alloc= 526b/s - PacketListener1P
[000034] user= 0.00% sys= 0.02% alloc= 1537b/s - Proxy:ExtendTcpProxyService1
[000049] user= 0.00% sys= 0.02% alloc= 6011b/s - JMX server connection timeout 49
[000032] user= 0.00% sys= 0.01% alloc= 0b/s - DistributedCache
https://github.com/aragozin/jvm-tools/blob/master/sjk-core/COMMANDS.md#ttop-command
Available via PerfCounters

MBeans: memory
• Memory geometry information
• Collection count
• Last collection details
 for each collector
• GC events available as notifications
since Java 7

SJK: GC
[GC: Copy#1806 time: 7ms interval: 332ms mem: Eden Space: 108032k-108032k->0k[max:191168k,rate:-325397.59kb/s] Tenured
Gen: 162185k+14k->162199k[max:477888k,rate:42.22kb/s] Survivor Space: 235k-13k->222k[max:23872k,rate:-41.93kb/s]]
Gen: 162418k+0k->162418k[max:477888k,rate:0.00kb/s] Survivor Space: 1k+0k->1k[max:23872k,rate:0.24kb/s]]
Total
Copy[ collections: 28 | avg: 0.0065 secs | total: 0.2 secs ]
MarkSweepCompact[ collections: 0 | avg: NaN secs | total: 0.0 secs ]
https://github.com/aragozin/jvm-tools/blob/master/sjk-core/COMMANDS.md#gc-command

MBeans: diagnostic commands
com.sun.management:type=DiagnosticCommand
com.sun.management:type=HotSpotDiagnostic
• Forcing GC / GC log rotation
• Head dump
• Flight recoder
• Changing --XX options
• etc
Java 8

JVM Attach API
• List JVM processes
• Attach to JVM by PID
• Send control commands
 heap dump / histogram
 stack dump
• Inspect system properties and VM options
• Launch instrumentation agents
https://github.com/gridkit/jvm-attach

SJK: hh --dead
Dead object histogram
 Similar to jmap –histo
 Invoke jmap –histo two time
 all heap objects
 live heap object
 calculates difference
 Can show top N rows
https://github.com/aragozin/jvm-tools/blob/master/sjk-core/COMMANDS.md#hh-command

SJK: hh --dead
1: 19117456 2038375696 [C
2: 9543865 441272568 [Ljava.lang.Object;
3: 13519356 432619392 java.util.HashMap$Entry
4: 12558262 301398288 java.lang.String
5: 7193066 287722640 org.hibernate.engine.spi.CollectionKey
6: 619253 160678888 [I
7: 4710497 113051928 org.jboss.seam.international.Messages$1$1
8: 571327 100876880 [Ljava.util.HashMap$Entry;
9: 1436183 57447320 org.hibernate.event.spi.FlushEntityEvent
10: 1661932 53181824 java.util.Stack
11: 209899 52047904 [B
12: 1624200 51974400 org.hibernate.engine.internal.Cascade
13: 929354 44608992 java.util.HashMap
14: 1812762 43506288 org.hibernate.i.u.c.IdentityMap$IdentityMapEntry
15: 850157 34006280 java.util.TreeMap$Entry
16: 1044636 25071264 java.util.ArrayList
17: 1340986 23423328 [Ljava.lang.Class;
18: 710973 22751136 java.io.ObjectStreamClass$WeakClassKey
19: 885164 21243936 org.hibernate.event.internal.WrapVisitor
20: 885126 21243024 org.hibernate.event.internal.FlushVisitor
...
Total 95197823 4793878008
https://github.com/aragozin/jvm-tools/blob/master/sjk-core/COMMANDS.md#hh-command

SJK: jps
JDK’s jps on steroid
 Uses attach API
 Lists VMs
 Filtering by JVM system properties
 Prints property values
 Prints effective –XX options
https://github.com/aragozin/jvm-tools/blob/master/sjk-core/COMMANDS.md#jps-command

SJK: jps
My favorite command
> sjk jps -pd PID MAIN duser.dir XMaxHeapSize
90543 sjk-0.3.1-SNAPSHOT.jar /var/vas_sdk_test_server -XX:MaxHeapSize=32126271488
5315 WrapperSimpleApp /var/vas_sdk_test_server/vas-sdk-test-13030 -XX:MaxHeapSize=4294967296
11094 WrapperSimpleApp /var/vas_sdk_test_server/vas-sdk-test-13020 -XX:MaxHeapSize=4294967296
993 Main /var/gedoms-uat/private/rtdb_1 -XX:MaxHeapSize=12884901888
56603 AxiomApplication /var/gedoms-uat/private/gedoms_1 -XX:MaxHeapSize=2147483648
24046 WrapperSimpleApp /var/sonar/sonar-3.6.2/bin/linux-x86-64 -XX:MaxHeapSize=536870912
https://github.com/aragozin/jvm-tools/blob/master/sjk-core/COMMANDS.md#jps-command

Perf counters
 Based on shared memory
 safe for target JVM
 Flat data model
 misc JVM counters
 true GC CPU usage data
 you can add own counter programmatically

Stack Trace Sampling
Capture
• Dump stack traces via local connection
• Store in highly compressed dump
10-30 bytes per trace
Analysis
• Frame frequency
• Conditional frame frequency
• Traces classification histogram
https://github.com/aragozin/jvm-tools/blob/master/sjk-core/COMMANDS.md#stcap-command

Stack Trace Sampling
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Base
other
DefaultServlet.doGet
LifecycleImpl.render
LifecycleImpl.execute
WorkItemController.doselect
Seam bean interceptor - lock contention
Seam bean interceptor - inject/disinject/outject
ResourceBundle - getObject
ResourceBundle - missing resource
Faceletscompile
Hibernate (rest)
Hibernate (autoFlush)
JDBC

Working with heap dumps
Java API to traverse heap dump object graph
Available at https://github.com/aragozin/jvm-tools/tree/master/hprof-heap
 Based on NetBeans profiler library
 No temporary files used
 Fixed generic method signatures
 Improved performance
Useful for
 In-place processing of large heap dumps
150 GiB is my personal record
 Write domain specific heap usage reports

HeapPath
 Convenient way to extract value from dump
 Error proof
 Handles String, primitives/boxed and arrays
myfield1.myfield2.myfield3
myarrayfield[0].myfield
myarrayfield[*].myfield
myarrayfield[*][*]
myfield1.*.myfield3
[*].value(MyClass)
myhashmap?entrySet[key=description].value

See also
https://github.com/vlsi/mat-calcite-plugin
Heap dump meets SQL

SJK Summary
Visit https://github.com/aragozin/jvm-tools
 Single executable JAR
 Command line interface
 Exploits JMX / Attach API / PerfCounters
 Sampling profiler included
 Extensible commands
 Write commands for your own application

Sigar
System Information Gatherer And Reporter
https://github.com/hyperic/sigar
• Cross platform
• Common system metrics
 CPU, Context switches, IO, etc
• Java bindings
 Self extracting JAR: org.gridkit.lab:sigar-lib:1.6.4

BTrace
Visit https://kenai.com/projects/btrace
Instrumentation profiling
 Inject code snippets written in Java
 CLI or Java API to use
 Extendible

BTrace
@OnMethod(clazz = "org.jboss.seam.Component",
method = "/(inject)/")
void entryByMethod2(@ProbeClassName String className, @ProbeMethodName String methodName,
@Self Object component) {
if (component != null) {
Field nameField = field(classOf(component), "name", true);
if (nameField != null) {
String name = (String)get(nameField, component);
Profiling.recordEntry(bench,
concat("org.jboss.seam.Component.", concat(methodName, concat(":", name))));
}
}
}
@OnMethod(clazz = "org.jboss.seam.Component",
method = "/(inject)/",
location = @Location(value = Kind.RETURN))
void exitByMthd2(@ProbeClassName String className, @ProbeMethodName String methodName,
@Self Object component, @Duration long duration) {
if (component != null) {
Field nameField = field(classOf(component), "name", true);
if (nameField != null) {
String name = (String)get(nameField, component);
Profiling.recordExit(bench,
concat("org.jboss.seam.Component.", concat(methodName, concat(":", name))), duration);
}
}
}

Flight Recorder
+ Accessible via JMX
+ Targeting JVM internals
+ Low overhead
‐ Non-compact file format
‐ Biased profiling
‐ Weak support for thread sampling

Self profiling benchmarks
Memory allocation regression tests
 assert for memory consumption using thread’s
allocation counter
Microbenchmarks
 MonitorGCeventstoexcluderesultaffectedbyGCpause
 Track CPU usage
 Thread sampling during benchmark

Performance tests
Nimble – framework for automated distributed performance testing
https://github.com/gridkit/nimble
https://code.google.com/p/gridkit/source/browse/grid-lab/trunk/examples/zk-benchmark-sample/
End – to – End automation
 Setup environment
 Run test scenarios
 Capture application KPI
 Capture metrics for OS and Java processes
 Integrated profiling with BTrace
 Single output data file

Profiling in production
In-house continuous query engine
 20+ applications
 Different environments, support teams, etc
 A lot of performance challenges
Built-in self profiling – currently in pilot
 Thread sampling
 CPU / allocation tracing
 Application specific diagnostics
 Fully encapsulated in application itself
Threading MBean performance
depredate for multithreaded access

Heap analyzer
In-house continuous query engine
 Relational graph up to few thousand nodes
 High memory consumption
Heap dump reporter automatically generates
 Memory consumption by operators
 Row count per operator
 Graph topology
 In Excel friendly format 

StackViewer
Visual tools
for thread dump
analysis
https://github.com/aragozin/stackviewer

Heap dump API + scripting
Coding in Java works well, but
 Reports are not interactive
 Slow trial and error turn around
Howaboutinteractive consoleforheapanalysis?
 bean shell / groovy ?
 how to do code completion in console?

Big Brother 4 J
We have already done it for performance testing
 Project detection
 Metrics capturing
 Integrated profiling sampling + instrumentation
 All metric in one place
How about ?
 Standalone tool for production
 Detecting specific Java processing
 Creating flight recording automatically
 In hyper dense file format

Thank you
Alexey Ragozin
alexey.ragozin@gmail.com
http://blog.ragozin.info
- my technical blog
http://github.com/aragozin
http://github.com/gridkit
- my open source projects

Java profiling Do It Yourself

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