michigan oracle users summit 2020

MICHIGAN ORACLE USERS SUMMIT 2020MONDAY OCTOBER 26 – THURSDAY OCTOBER 29, 2020

VIRTUAL EVENT

Optimizing WebLogic and Maximizing

Application Uptime

Ahmed Alomari

Agenda

• Architecture

• OA Framework

• Infrastructure & JVM Tuning

• Applications Connection Pool

• Thread Dumps

• Heap Dumps

• Q & A

Architecture

R12.2 Architecture

• R12.2 uses Oracle Fusion Middleware (11gR1)

• WebLogic Server (WLS) -10.1.3.6

• WebLogic JSP Compiler and Engine 11.1.1.9

• Dual File System (FS1 & FS2) – Run and Patch Filesystems

• ADOP (online Patching) utility

• 64 bit Java Support

– Can deploy Managed servers with larger heaps such as 8GB

– Useful for components with large memory footprints

• Oracle Configurator

• Reporting

• Large number of online users

• New Middle Tier Code level checker (MT –ETCC)

Terminology

• JVM – Java Virtual Machine

• JRE – Java Runtime Environment

• JDK – Java Development Kit

• Java SE – Java Standard Edition

• Java EE – Java Enterprise Edition

• Java ME – Java Micro Edition

• Hotspot – Oracle (Sun’s) VM Implementation

➢Server VM and Client VM

• JNI - Java Native Interface (Native Applications)

Terminology

• JSP - Java Server Pages

➢Web pages which can embed Java, JavaScript, and/or HTML. Usually compiled into a servlet.

➢Located in $OA_HTML

• JDBC – Java Database Connectivity

➢ Interface for SQL execution for Java Applications.

• Servlets – Server side Java code used to interact with Web based applications.

➢Configurator

➢ iPayment

➢AppsLogin

Terminology

• Applet – Client side Java code such as Java code which runs inside a browser [JRE Plug-in or Java Web Start (JWS)]

– Oracle WebForms

• javac – Compiler used to compile java source code files into class files (i.e. byte code).

• JAR – Java Archive

➢ Typically used to package an Application including class files, configuration files, properties, manifest, etc..

• Manifest – Descriptor file

• JAR Signing

➢ Attach a digital signature to the JAR file in order to improve security.

Terminology

• Class file

➢Well-defined format of compiled Java source (i.e. byte code).

• Package

➢Allows class files to be organized into a hierarchy

• java.lang

• java.util

• oracle.apps.fnd.common

• Class hierarchy

➢oracle.apps.fnd.common.WebAppsContext →

• $JAVA_TOP/oracle/apps/fnd/common/WebAppsContext.class

Terminology

• JDK Vendors

➢Oracle – Linux, Solaris, Windows, macOS

➢ IBM – AIX, Linux, z/OS, Windows

➢HP – HP UX

➢JRockit - Linux, Solaris, Windows

➢Extended Support ended December 2018

➢Oracle JVM – DB Server platforms.

➢GraalVM - Oracle

Terminology

• Web Container

➢A Java Application Server which provides deployment and runtime services

➢JSP engine

➢Pooling Services

➢Thread Pool

➢JDBC Connection Pool

➢Security

➢Logging

➢Transaction Management

➢Cluster Services

Terminology

• Web Container

➢Oracle Containers for J2EE (OC4J)

➢Extended support through June 2017

➢Oracle WebLogic

➢ IBM WebSphere

➢Apache Tomcat

➢RedHat JBoss

➢GlassFish (Open Source)

Architecture

Architecture• HotSpot VM / Mixed-Mode VM

➢ Compiles “hot” classes using thresholds and other criteria into native machine code.

• Oracle HotSpot VM provides Client and Server compilers.

• -server• -client

➢ Uses background thread (CompilerThread0)• To perform compilation.

➢ Switch -XX:+PrintCompilation can be used to report compilation activity including method names.

• java.lang.String::charAt (33 bytes)• java.lang.String::hashCode (60 bytes)

Architecture

• Java Object Life Cycle

Architecture

• Finalizers

➢ Object has been declared unreachable.

➢ The finalize() method on the object is invoked.

Architecture

• Leaks

webAppsCtx = new WebAppsContext(l_dbc);

requestType = httpservletrequest.getParameter("requestType");

String jvm_url =

webAppsCtx.getProfileStore().getProfile("APPS_FRAMEWORK_AGENT");

webAppsCtx.createAnonymousSession();

connection = webAppsCtx.getJDBCConnection();

. . . . . . .

} catch (Exception e)

MessageErrorHandler(e);

Architecture

• Garbage Collection

➢ Process of re-claiming memory for objects which are

either no longer reachable (i.e. strong reference cleared)

or object reference type permits collection.

➢ Memory leaks in Java are due to references which are not

cleared such as adding objects to a collection without

removing the entry or setting the reference to null.

• Connection leaks

• Cursor leaks

• Data Structure leaks (hash tables, hash maps, other

collection types, etc..)

➢ For example, cursor leaks are fixed by calling the close()

method on the statement object (i.e. reference is cleared

therefore making the object collectable).

Architecture

• Garbage Collection

➢ The JVM provides various collectors based on the heap

being collected as well as the JVM configuration options.

➢ Garbage Collection can be monitored via the following

switches:

• -verbosegc

– Enables GC messages

• -XX:+PrintGCDetails

– Records heap level details of GC event

• -Xloggc

– Redirects GC messages to a dedicated log file

– Can use tools to open the GC log file and plot the data

points.

Architecture

• Collectors➢ Serial Collector (-XX:+UseSerialGC)

➢ Parallel New Space Collector • -XX:+UseParallelGC / -XX:ParallelGCThreads

➢ Concurrent Collector (CMS)• -XX:+UseConcMarkSweepGC

• Tries to minimize GC Pause times for stop the world collections.

• CMS optimal for old generation collections as well as Applications which require a large permanent footprint (i.e. large data caches).

• Much more efficient than the conventional Full GC.

➢ Garbage First (G1) Garbage Collector – 1.7+• Successor to CMS

• -XX:+UseG1GC

• Utilizes compaction

• Divides heap into regions rather than by generation.

– Z Garbage Collector (ZGC) – JDK 11• Low latency garbage collector

Architecture

• Java Heaps (-Xmx/-Xms)➢ Xmx (maximum heap size)

➢ -Xms (minimum heap size at startup)

• Heap segment is memory mapped or a shared memory segment is created if large pages is used.

➢ Young Generation

• Eden (Nursery)

– NewRatio or NewSize/MaxNewSize

• Survivor Space

– Can be tuned via SurvivorRatio

➢ Tenured Generation (Old Generation)

➢ Meta Space heap (Permanent Generation)

• MaxMetaspaceSize (formerly PermSize and MaxPermSize)

• -XX:MetaspaceSize / -XX:MaxMetaspaceSize

• Code Cache (classes)

• Constants

• Intern strings

Architecture

• Java Heaps (-Xmx/-Xms)

➢ Total OS memory size will be the sum of the value of:

• Xmx + MaxMetaspaceSize + Thread Stacks + Control

Structures

➢ Gather and review verbose GC data to optimally size the

JVM heaps.

• Need to understand the permanent memory footprint (i.e.

tenured generation footprint after caches are loaded and

steady state achieved).

• Need to understand object creation and allocation rates.

• Need to understand lifespan of transient objects.

• Need to understand user level concurrency traffic as well as

end-user response time SLAs.

• Choose optimal collector based on above data points.

OA Framework

Database

OA Framework

Statement Cache

Connection Pool

Metadata Cache

Data Cache

HTML Generation

JSP Engine

OA.jsp / OAP.jsp

Module Code

Controller Object

OA Framework Architecture

• Java Server Page Source (JSPs)

➢$OA_HTML

• Java Server Page Cache

➢$COMMON_TOP/_pages

• Java Classes

➢$JAVA_TOP

Java Server Pages (JSP)

• Java Server Page (JSP) Execution

➢Upon JSP invocation, the JSP page cache is

examined.

• If a cache entry exists, the JSP class is executed.

• If a cache entry does not exist, the JSP is

processed as follows:

– Translation (.jsp -> .java)

– Compilation (.java -> .class)

Java Server Pages (JSP)

• OA.jsp

➢Centralized JSP which executes OA FWK based

pages such as the Home Page.

➢Uses redirection to render the relevant page.

• RF.jsp

➢Centralized JSP which is used to execute standard

web functions such as:

• Launching Oracle Forms

• Launching Certain Web pages

OA Framework Architecture

• User navigates to the OA FWK Page such as iExpenses

or iProcurement

➢Page Metadata is read and loaded into the MDS

➢Controller Page Object is invoked

➢Controller Page Object invokes server side

components such as the Entity Object or View Object.

• About this Page link can be used to display page

components.

Infrastructure Tuning

• Ensure kernel/shell limits are set sufficiently as per

the load.

• Low settings can result in JVM errors, hangs, or

OutOfMemoryError(s).

• /etc/security/limits.confaebizprd hard core unlimited

aebizprd hard nofile 131072

aebizprd hard nproc 131072

aebizprd soft core unlimited

aebizprd soft nofile 131072

aebizprd soft nproc 131072

• Ensure optimal performance of NAS device and the

shared application filesystem (NFS)

• OHS and JVM logs and output files (runtime)

• JVM performance is impacted due to NAS latency.

• Utilize NFS V4 for application file system mounts

– Ensure NAS device supports V4

– nas-app-prod:/app01 on /app01 type nfs4

(rw,relatime,vers=4.0,rsize=64k,wsize=64k,namlen=2

55,soft,nordirplus, local_lock=none)

• Monitor CPU and memory utilization on the

application tier hosts.

– Top processes (by CPU and memory)

– Leverage EM grid or install OSWatcher.

• Monitor Entropy pool to ensure sufficient availabilityIf Entropy values are low or exhausted, the JVM can hang

with threads blocked waiting on random key generation.

applmgr> cat /proc/sys/kernel/random/entropy_avail

Might need to switch to /dev/urandom or use options to increase

Entropy availability.

JVM Tuning

Application Tier - JVM

• Ensure you are running a current version of the JDK as

well as current patch set.

Version

Current

Patchset

MetaLink Note Applications

Version

7.0 Update 281

(31856324)

1467892.1 (12.1)

1530033.1 (12.2)

12.1.3 /12.2.X

8.0 Update 271

(31856303)

393931.1 (R12) JRE

• JDK 7.0 New Features➢ Invokedynamic instruction for dynamic languages.

➢ Garbage-First (G1) Garbage Collector.

➢ Improved Class loading➢ Parallel ClassLoader

➢ try with block➢ java.lang.AutoCloseable

➢ Tiered Compilation

➢ -XX:+TieredCompilation

➢ Compressed Ordinary Object Pointers

➢ -XX:+UseCompressedOops

➢ NUMA Aware Collectors

➢ -XX:+UseNUMA

➢ Switch statement can reference String Objects as expressions.

➢ ThreadLocalRandom

➢ Improve performance of random number generators.

• JDK 1.5 JVM monitoring tools

➢ jps

➢ jstat

➢ jconsole

➢ jmap (utility to obtain heap information)

• JDK 1.6

➢ jhat (Memory Analysis tool)

➢ jmap enhanced to specify heap dump file name/path.

➢ JDK 1.7

➢ jcmd (diagnostic commands utility)

➢ jvisualvm (JVM monitoring tool)

➢ JDK 1.8

➢ jmc (Java Mission Control)

➢ jmc (Java Mission Control) – Flight Recorder

• Set initial and max. heap sizes appropriately. Sizes

below are starting points and should be adjusted as per

the load and footprint.

Usage Model Recommended Starting Heap

Small Xms/Xmx=1G

Medium Xms/Xmx=3-4G

Large Xms/Xmx=6-8G

• Add sufficient managed servers across the app-tier nodes to handle the load.

• Minimum two OACore managed servers per app tier host.

• Ensure sufficient CPU and memory exist to support two managed servers plus other processes.

• Use a hardware load balancer (VIP) to load balance the requests across the OACore managed servers.

• Refer to MOS 1905593.1.

perl <AD_TOP>/patch/115/bin/adProvisionEBS.pl \

ebs-create-managedserver -contextfile=<CONTEXT_FILE> \

-managedsrvname=oacore_server4 -servicetype=oacore \

-managedsrvport=21205 -logfile=<APPLRGF>/TXK/addMS_oacoreserver4.log

Application Tier – Logging

• Set logging level to Notice (Severity Levels)– WebLogic Admin Console for oacore_server<n>

• Logging tab

Application Tier – Logging

• Set logging level to Notice (Severity Levels)

➢ Review JVM log files for exceptions or errors

• 12.2: $EBS_DOMAIN_HOME/servers/oa*/logs/

– oacore_server2.out

– oacore_server2.log

– OPMN logs:» $IAS_ORACLE_HOME/instances/*/diagnostics/logs/OPMN/opmn

• 12.1: $INST_TOP/logs/ora/10.1.3/opmn/*oacore*– oacore_default_group_<n>

– oacorestd.out

– oacorestd.err– log4j:

» log4j.rootLogger=error, stdout, R

Application Tier – JVM

• Enable verbose GC

– 12.2: WebLogic Admin Console

• Configuration->Server Start->Arguments

263888.839: [GC [PSYoungGen: 378131K->9061K(393280K)] 1175648K->807594K(1212480K), 0.0249310 secs] [Times:

user=0.19 sys=0.01, real=0.02 secs]

264062.982: [Full GC[Unloading class sun.reflect.GeneratedMethodAccessor443]

[PSYoungGen: 2107K->0K(392768K)] [PSOldGen: 805666K->247375K(819200K)] 807774K->247375K(1211968K) [PSPermGen:

54677K->53972K(71680K)], 2.6600860 secs] [Times: user=2.63 sys=0.03, real=2.66 secs]

New Space

Elapsed Time

Size Before

GC Size After

Perm. Gen

Type of GC

• Review verbose GC data

Application Tier – JVM

• Jstat• S0C Current survivor space 0 capacity (KB).

• S1C Current survivor space 1 capacity (KB).

• S0U Survivor space 0 utilization (KB).

• S1U Survivor space 1 utilization (KB).

• EC Current eden space capacity (KB).

• EU Eden space utilization (KB).

• OC Current old space capacity (KB).

• OU Old space utilization (KB).

• PC Current permanent space capacity (KB).

• PU Permanent space utilization (KB).

• YGC Number of young generation GC Events.

• YGCT Young generation garbage collection time.

• FGC Number of full GC events.

• FGCT Full garbage collection time.

• GCT Total garbage collection time.

• jstat -gc 298291; jstat -gcutil 298291

• S0C S1C S0U S1U EC EU OC OU PC PU YGC YGCT FGC

FGCT GCT

• 294400.0 303616.0 0.0 141953.0 6370816.0 1796791.0 13981696.0 2371051.0 1048576.0 194275.0 49

8.497 0 0.000 8.497

• S0 S1 E O P YGC YGCT FGC FGCT GCT

• 0.00 46.75 28.20 16.96 18.53 49 8.497 0 0.000 8.497

Application Tier – Session Timeout

• Set the served session timeout to 30 minutes

➢12.2: Set the profile “ICX:Session Timeout”

– WebLogic: timeout-secs (1800)

➢Larger timeout values increase overall JVM

memory footprint.

Application Tier – Web Applications

– Ensure the users are trained to use the Logout or Home global buttons

when completing their transactions.

• Ensure users do not use the browser close (“x”) link.

– Logging out gracefully releases the memory and corresponding

resources (i.e. connections, etc..)

• Avoids memory leaks and timeout based invalidation.

Connection Pool

Application Tier – Connection Pool

• Apps Connection Pool – Enable Test Connection– WebLogic->Configuration->EBSDataSource->Connection Pool-

>Advanced

• Apps Connection Pool (dbc configuration)

➢ Apps Supports the use of Services for RAC load balancing or

failover.

• dbc parameter APPS_JDBC_URL

APPS_JDBC_URL=jdbc\:oracle\:thin\:@(DESCRIPTION\=(LOAD_BALANCE\=YES)(FA

ILOVER\=YES)(ADDRESS_LIST\=(ADDRESS\=(PROTOCOL\=tcp)(HOST\=db1host)(POR

T\=24601))(ADDRESS\=(PROTOCOL\=tcp)(HOST\=db2host)(PORT\=24601)))(CONNE

CT_DATA\=(SERVICE_NAME\= ebizprodOA)))

• WebLogic Connection Pool Monitoring (12.2)

• WebLogic Console->Data Source->Monitoring-

>Statistics

• Process Identification (GV$SESSION)

– Allows you to map the JDBC session from v$session to a particular JVM

process.

SID MACHINE PROCESS MODULE LOGON

---- ------------------------- ------------ ------------------ -----------------

41 aptier1.us.oracle.com 23806 JDBC Thin Client 10/08/20 17:26:43

. . . . . . .

aptier1{apps_a}-> ps -ef | grep 23806

apps_a 23806 23804 53 17:26:40 pts/20 8:55 /R12/fs1/EBSapps/comn/util/jdk64/bin/java -

Dweblogic.Name=oacore_server2 -DCLIENT_PROCESSID=24314 -server -verbose:gc . . . . . . .

• Ensure Inactive Connection Timeout is set to zero (12.2).

– Only enable if debugging connection leaks, and reset to

zero after collecting debug logs.

– A non-zero values can actually create additional connection

leaks due to the WebLogic Shrink activity.

• Ensure Deadman detection is enabled in sqlnet.ora for

the DB listener

– $TNS_ADMIN/sqlnet.ora

• SQLNET.EXPIRE_TIME= 10

• If not enabled, connections can hang due to TCP timeouts,

firewall rules, abnormal connection terminations, etc..

• Ensure sqlnet.ora entry is present for all relevant listeners

used by the application:

– DB listener (AutoConfig instance listener directory)

– GI/ASM listeners

– Scan listener

Application Tier – WebLogic Console

• Managed Server Performance page

➢Monitor JVM metrics

➢Heap Utilization

➢Garbage Collections

➢Thread information

➢Stuck Threads

Application Server – WebLogic Console

WebLogic Tuning

• Monitor Thread and Connection Pools

– Thread Count

– Maximum number of connections

• JDBC Ping Check Tuning

– Consider disabling if connections are stable and not hard-closed due to

firewall or inactivity termination.• Test Connections On Reserve

• Test Frequency

• Enable JDBC Statement Caching– Test thoroughly and watch for cursor leaks

• Utilize Hardware Load Balancers in place of Web Server clustering

• Monitor Heap utilization and GC traffic

WebLogic Tuning

• Monitor Long Running and Stuck Threads– Stuck Thread Max Time

– Stuck Thread Timer Interval

Java Thread Dumps

Application Tier – Thread Dumps

➢ Thread dumps show the stack trace for each thread

that is alive.

➢ To generate a thread dump, identify the process id of

the JVM process.

• Then, execute the following:

-kill –QUIT <pid>

➢ Thread dumps show deadlocks which can cause the

JVM to stop responding to user requests. If that’s the

case, the JVM should be restarted.

➢ Helps identify deadlocks, infinite loops, long running

queries submitted by the user, etc..

➢ Thread dumps show the stack trace for each thread

that is alive.

➢ To generate a thread dump, identify the oacore

Managed Server name and click on the Dump Thread

Stacks button.

Application Tier – Thread Dumps2020-10-09 14:58:31

Full thread dump Java HotSpot(TM) 64-Bit Server VM (24.201-b11 mixed mode):

"Worker-5" daemon prio=10 tid=0x00007f17d402b000 nid=0x5e751 in Object.wait() [0x00007f1712bfd000]

java.lang.Thread.State: WAITING (on object monitor)

at java.lang.Object.wait(Native Method)

at oracle.ias.cache.TaskQ.waitForWork(TaskQ.java:255)

- locked <0x0000000312f2f250> (a oracle.ias.cache.TaskQ)

at oracle.ias.cache.TaskQ.getTask(TaskQ.java:138)

at oracle.ias.cache.WorkerThread.run(ThreadPool.java:303)

"Worker-4" daemon prio=10 tid=0x00007f16f8023000 nid=0x5e750 in Object.wait() [0x00007f17397fc000]

"Worker-2" daemon prio=10 tid=0x00007f175d85a000 nid=0x5e6cb in Object.wait() [0x00007f1713ffe000]

Found one Java-level deadlock:

=============================

"Thread-65103":

waiting to lock monitor 0x0813e334 (object 0xb4006318, a

oracle.jbo.common.ampool.SessionCookieImpl$SessionCookieLock),

which is held by "Thread-65088"

"Thread-65088":

waiting to lock monitor 0x0813e374 (object 0xb3fa1418, a org.apache.jserv.JServSession),

which is held by "Thread-65103"

Java stack information for the threads listed above:

===================================================

"Thread-65103":

at oracle.apps.fnd.framework.webui.OAHttpSessionCookieImpl.timeout(OAHttpSessionCookieImpl.java:607)

- waiting to lock <0xb4006318> (a oracle.jbo.common.ampool.SessionCookieImpl$SessionCookieLock)

at oracle.jbo.http.HttpSessionCookieImpl.timeout(HttpSessionCookieImpl.java:146)

at oracle.jbo.http.HttpContainer.fireTimeout(HttpContainer.java:512)

at oracle.jbo.http.HttpContainer.timeout(HttpContainer.java:232)

at oracle.jbo.http.HttpContainer.valueUnbound(HttpContainer.java:300)

at org.apache.jserv.JServSession.invalidate(JServSession.java:240)

- locked <0xb3fa1418> (a org.apache.jserv.JServSession)

. . . . . . . .

"Thread-65088":

at org.apache.jserv.JServSession.getValue(JServSession.java:293)

- waiting to lock <0xb3fa1418> (a org.apache.jserv.JServSession)

at oracle.jsp.provider.JspUniversalHttpRequest.getSession(JspUniversalHttpRequest.java:408)

at oracle.jsp.provider.JspRDRequest.getSession(JspRDRequest.java:144)

. . . . . . . .

• Java Thread dump output (standard out)

➢12.2: $EBS_DOMAIN_HOME/servers/oacore_server<n>/logs/oacore_server<n>.out

➢12.1:

• $INST_TOP/logs/ora/10.1.3/opmn/default_group~oacore~default_group*

• What should you look for?

➢Deadlocked threads.

➢Threads stuck in an infinite loop.

• Check to see if the stack is changing.

Java Heap Dumps

Application Tier – Heap Dumps

• Java Heap Dumps

➢Useful when trying to debug memory leaks, excessive footprint/garbage collection, and/or OutofMemoryErrors.

➢There are two types of heap dumps:

• Summary (histogram of all class instances and shallow size)

• Full heap dump (complete dump of the entire Java heap) which includes old generation and permanent generation.

-Can result in very large files depending on the heap sizes.

• Java Heap Dumps – Summary Heap Dump

➢Summary (histogram of all class instances and

shallow size)

• Can be generated using jmap

– jmap -histo:live <pid>

• Can be generated using a thread dump (kill -3) if

the JVM switch (-XX:+PrintClassHistogram) is

present. The summary histogram will be rewritten

to the oacore*.stdout log files (by default).

• Java Heap Dumps - Summary Heap Dumpnum #instances #bytes class name

----------------------------------------------

1: 21437694 686006208 com.sun.java.util.collections.HashMap$Entry

2: 5553282 646005184 [C

3: 19853550 476485200 oracle.apps.cz.dio.FieldCache

4: 615172 218915592 [Lcom.sun.java.util.collections.HashMap$Entry;

5: 315197 143264864 [B

6: 5539474 132947376 java.lang.String

7: 1453342 81990664 [Ljava.lang.Object;

8: 1545022 61800880 java.math.BigDecimal

9: 341887 54284456 <constMethodKlass>

10: 2119195 50860680 java.lang.Long

11: 341887 43778960 <methodKlass>

12: 283528 40828032 oracle.apps.cz.dio.model.DbBomOptionClass

13: 29342 37480752 <constantPoolKlass>

14: 615172 34449632 com.sun.java.util.collections.HashMap

15: 1004869 32155808 java.sql.Timestamp

16: 1124467 26987208 com.sun.java.util.collections.ArrayList

17: 1120206 26884944 java.lang.Double

18: 839012 26848384 EDU.oswego.cs.dl.util.concurrent.ConcurrentHashMap$Entry

19: 600378 24015120 oracle.apps.cz.utilities.LongHashMap$Entry

20: 29342 23976200 <instanceKlassKlass>

• Java Heap Dumps – Summary Histogram

– Quick to generate (several seconds)

• -XX:+PrintClassHistogram (and kill -3) is much faster

than jmap because it uses the native signal handler to

dump the heap.

– Good place to start when debugging leaks as it can help

you narrow down which objects are growing and which

objects consume the most memory.

• Once you have narrowed down the suspect objects, a

full heap dump can be generated to identify the root

cause and examine the reference graph.

• Java Heap Dumps – Full Heap Dump– Dumps all live objects to a heap dump file usually in hprof

format.

– Can be generated using jmap• jmap -heap:format=b <pid>

– Trigger a heap dump when an OutofMemoryError occurs

• -XX:+HeapDumpOnOutOfMemoryError

• -XX:HeapDumpPath=<path>

– Use Memory Profiling tools to analyze the heap dump:

• jhat (part of JDK)

– Can also compare two heap dumps which will help narrow down the objects which continue to grow

• Eclipse Memory Analyzer (MAT)

• NetBeans IDE (Memory Profiler)

References

• https://docs.oracle.com/javase/8/docs

• http://www.oracle.com/technetwork/tutorials/tutorials

-1876574.html

• http://www.oracle.com/technetwork/java/index.html

• http://bugs.java.com/bugdatabase

• http://www.oracle.com/technetwork/java/javase/docu

mentation/index.html

• http://www.oracle.com/technetwork/java/javaseprod

ucts/mission-control/java-mission-control-

1998576.html

www.mous.us

THANK YOU

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THANK YOU

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Thank You Q & A

World Class Managed Services

Application Performance Management

Leader in Oracle Performance Tuning

Application Development and Integrations

Upgrades and Cloud Implementations

aalomari@cybernoor.com Ph: (925) 924-0400

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