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Date: Fri, 14 Mar 2008 06:59:29 -0700 (PDT)
From: Bently Drake <bentlydrake@yahoo.com>
Subject: Re: Database connections grow after redeploy
To: Tomcat Users List <users@tomcat.apache.org>
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Memory leaks and deadlocks and CPU hogs! Java application developers often =
face these runtime problems. They can be particularly daunting in a complex=
 application with multiple threads running through hundreds of thousands of=
 lines of code -- an application you can't ship because it grows in memory,=
 becomes inactive, or gobbles up more CPU cycles than it should.=0A =0AHere=
 are some tools that can help you finding out your application performance.=
 You can monitor thread usages, memory leaks, instance count etc; also in c=
ase of web application you can find out the number of sessions, number of r=
equest per second, average response time, database connection time, error c=
ount etc.=0A =0A1 JProfiler: JProfiler is an award-winning all-in-one Java =
profiler. JProfiler's intuitive GUI helps you find performance bottlenecks,=
 pin down memory leaks and resolve threading issues. You can use it to moni=
tor a standalone java application or a web application.=0A =0Ahttp://www.ej=
-technologies.com/products/jprofiler/overview.html=0A =0AFeatures:=0A =0A=
=B7          Live profiling of a local session=0A=B7          Live profilin=
g of a remote session=0A=B7          Offline profiling=0A=B7          Snaps=
hot comparisons=0A=B7          Memory profiling=0A=B7          Heap walker=
=0A=B7          CPU profiling=0A=B7          Thread profiling=0A =0A =0A=0A=
 =0A =0A =0A =0A =0A =0A=0A =0A =0A =0A =0A =0A =0A=0A =0A =0A =0A2. Manage=
Engine=AE Applications Manager 8=0Ahttp://manageengine.adventnet.com/produc=
ts/applications_manager/applications-monitoring-features.html=0AApplication=
s Manager provides in depth monitoring of web applications, be it a CRM app=
lication, banking / finance application or any business critical applicatio=
n. Applications Manager can also help monitor the underlying infrastructure=
 which may consist of application servers, databases, systems, mail servers=
 and other Java/J2EE Applications. =0AThrough the application monitoring fe=
ature you can ensure the health and availability of your application server=
s through Microsoft .NET Monitoring, Oracle Application Server Monitoring, =
JBoss Monitoring, Tomcat Monitoring, WebLogic Monitoring, and WebSphere Mon=
itoring. Out-of-the-box support for databases through Oracle Monitoring, SQ=
L Server Monitoring, MySQL Monitoring, DB2 Monitoring is also present.=0A =
=0AApplications Manager helps ensure higher uptime by detecting and diagnos=
ing problems of application servers and their services faster=0A=0A =0A =0A=
 =0A=0A3. JMeter=0Ahttp://jakarta.apache.org/jmeter/=0A =0A =0AApache JMete=
r is a 100% pure Java desktop application designed to load test functional =
behavior and measure performance. It was originally designed for testing We=
b Applications but has since expanded to other test functions.=0A =0AApache=
 JMeter may be used to test performance both on static and dynamic resource=
s (files, Servlets, Perl scripts, Java Objects, Data Bases and Queries, FTP=
 Servers and more). It can be used to simulate a heavy load on a server, ne=
twork or object to test its strength or to analyze overall performance unde=
r different load types. You can use it to make a graphical analysis of perf=
ormance or to test your server/script/object behavior under heavy concurren=
t load=0A =0AApache JMeter features include: =0A=B7         Can load and pe=
rformance test HTTP and FTP servers as well as arbitrary database queries (=
via JDBC) =0A=B7         Complete portability and 100% Java purity . =0A=B7=
         Full Swing and lightweight component support (precompiled JAR uses=
 packages javax.swing.* ). =0A=B7         Full multithreading framework all=
ows concurrent sampling by many threads and simultaneous sampling of differ=
ent functions by seperate thread groups. =0A=B7         Careful GUI design =
allows faster operation and more precise timings. =0A=B7         Caching an=
d offline analysis/replaying of test results. =0A=B7         Highly Extensi=
ble: =0Ao        Pluggable Samplers allow unlimited testing capabilities. =
=0Ao        Several load statistics may be choosen with pluggable timers . =
=0Ao        Data analysis and visualization plugins allow great extendibili=
ty as well as personalization. =0Ao        Functions can be used to provide=
 dynamic input to a test or provide data manipulation. =0Ao        Scriptab=
le Samplers (BeanShell is fully supported; and there is a sampler which sup=
ports BSF-compatible languages) =0A =0A=0A =0A =0A =0A4 Lambda Probe (forme=
rly known as Tomcat Probe)=0Ahttp://www.lambdaprobe.org/d/index.htm=0A =0A =
=0A =0ALambda Probe (formerly Tomcat Probe) is a self sufficient web applic=
ation, which helps to visualize various parameters of Apache Tomcat instanc=
e in real time. Lambda Probe is designed to work specifically with Tomcat s=
o it is able to access far more information that is normally available to J=
MX agents.=0A =0AJVM memory usage monitor =0AJBoss compatibility =0ADisplay=
 of deployed applications, their status, session count, session object coun=
t, context object count, datasource usage etc =0AAbility to view deployed J=
SP files =0ADisplay of list of sessions for a particular application =0AGra=
phical display of datasource details including maximum number of connection=
s, number of busy connections and configuration details =0ADisplay of syste=
m information including System.properties, memory usage bar and OS details =
=0AAbility to show information about log files and download selected files =
=0AAbility to tail log files in real time from a browser. =0AAbility to int=
errupt execution of "hang" requests without server restart =0ASupport for D=
BCP, C3P0 and Oracle datasources =0ASupport for Tomcat 5.0.x and 5.5.x =0AS=
upport for Java 1.4 and Java 1.5 =0A =0A=0A=0A =0A =0AAnd here are some mor=
e that you can explore=0A =0ATools for tracking down memory leaks.=0AXPCOM =
Memory Leak tools (this document also has information on Mozilla's other me=
mory leak tools). See also a tutorial on using these tools and the refcount=
 balancer. =0ARational Purify=AE. (Commercial) =0AGlowCode. (Commercial) =
=0AElectricFence. =0A"Electric Fence ... uses the virtual memory hardware o=
f your system to detect when software overruns the boundaries of a malloc()=
 buffer. It will also detect any accesses of memory that has been released =
by free(). Because it uses the VM hardware for detection, Electric Fence st=
ops your program on the first instruction that causes a bounds violation." =
=0ASpecifically, it works by placing each heap allocation on its own VM pag=
e. Since the dynamic footprint of the browser is pretty large, this may mak=
e it tough to use "in real life". =0ALeaky. This is a home-grown tool that =
Kipp put together: =0A"Its a tool called leaky. What it does it help you tr=
ack down memory leaks and some kinds of memory corruption. It also has entr=
y pointers for logging addref/release calls. The key thing that leaky does =
is this: it logs all calls to malloc/free/realloc/new/delete into a log fil=
e. The logging data includes information about size and address, as well as=
 the *call stack of the operation*. The leaky program then can translate th=
e call stack data from addresses into symbols and then dump the data out." =
* =0Arefcount balancer. This is another home-grown tool that does finer-gra=
ined instrumentation and allows you to focus on specific objects rather tha=
n entire runs. =0AInsure++=AE. (Commercial) Evaluation copy is free. Linux =
version. =0ALeakTracer. =0Accmalloc. =0Adebauch Dead? =0Amemwatch. =0AGeode=
sic Systems' GreatCircle Dead? Scott Furman has done some preliminary work =
to get this product working with Mozilla. =0AJulian Seward writes of Valgri=
nd, an open-source memory debugger and profiler for Linux/x86: `Snapshots 2=
0020511 and later of the tool are able to run Mozilla correctly on both Red=
 Hat 6.2 and 7.2. It will also do detailed low-level I1/D1/L2 cache profili=
ng, so you can see which bits of Mozilla create cache misses. You'll need t=
he patch from bug 124335 if working with versions prior to 1.0RC2. =0AProfi=
ling=0AThe following tools are used to measure product performance.=0ARatio=
nal PurifyPlus. (Commercial) Used to be called Rational Quantify. =0Aqfy2ht=
ml.pl. A Perl script for munging Quantify 6.0 output into hyperlinked HTML =
to share with your friends. Run Quantify, save your results as text, and th=
en let this thing rip. =0AQuantifying Mozilla on Solaris. Instructions on h=
ow to make Quantify play nicely with Mozilla on Solaris. =0AFor performance=
 work on Mac, you can use either the Metrowerks Profiler (on subsets of the=
 codebase), or Apple's Instrumentation SDK. For details, see the page on Ma=
c performance. =0Ahiprof. A hierarchical instruction profiler for Digital U=
nix. There is an online tutorial, courtesy Jim Nance (jim_nance@yahoo.com):=
 =0A"I like it because it does not require you to recompile the program, be=
cause it give accurate times for callers, and because it comes with DU so t=
hat everyone developing there should already have it." * =0Ajprof. Sampling=
 profiling tool by Jim Nance that runs on RedHat 6.1, 6.2. =0AMOZ_TIMELINE =
Timing instrumentation. Extremely useful for app startup measurements. =0Ae=
azel profilers. Two profiling tools from Eazel/gnome.org, runs on Linux. =
=0AJS Runtime Profiler. Profile JavaScript usage, dumps output to a file. =
=0ASysinternals utilities. Win9x/Me/NT/2K utilites for monitoring system us=
age. CPU/Mon, Diskmon, Filemon, Regmon, etc. =0Agprof. Part of the GNU Binu=
tils. Back in May 1999 there were rumors that gprof had trouble with dynami=
cally linked and loaded objects (like Mozilla). Currently (March 2006) gpro=
f is still being developed, so hopefully that's no longer true (assuming it=
 ever was). The link to the gprof manual above is years out of date but, at=
 the time of writing, it's the latest version of the manual on gnu.org. To =
get an up to date version of the manual, get the gprof source and run |. co=
nfigure; make html| in the gprof source directory. =0A =0A =0A=0A=0A=0A----=
- Original Message ----=0AFrom: David Cassidy <david@twocats.co.uk>=0ATo: T=
omcat Users List <users@tomcat.apache.org>=0ASent: Friday, March 14, 2008 7=
:13:17 PM=0ASubject: Re: Database connections grow after redeploy=0A=0Atry =
netbeans=0Aits free and the profiler will watch all your objects being crea=
ted.=0Ait will also work with snapshots...=0A=0A=0A=0A=0AOn Thu, 2008-03-13=
 at 20:56 +0200, Juha Laiho wrote:=0A> Scott McClanahan wrote:=0A> > > On T=
hu, 2008-03-13 at 12:02 -0400, Christopher Schultz wrote:=0A> > > Caldarale=
, Charles R wrote:=0A> > |> From: Scott McClanahan [mailto:scott.mcclanahan=
@trnswrks.com]=0A> > |> Subject: Re: Database connections grow after redepl=
oy=0A> =0A> > | As far as the continuing data base connections, I can only =
speculate=0A> > | that the prior instances of the webapp are still active, =
thereby=0A> > | preventing cleanup of their resources.=0A> =0A> > > I agree=
.. Scott: are you able to run your application through a tool that=0A> > > a=
llows you to observe the heap and object graphs?=0A> =0A> > > More likely i=
s that one or more application-level objects has retained a=0A> > > referen=
ce to a specific Connection object, which, of course, retains=0A> > > refer=
ences back to the connection pool that created it. I would check=0A> > > an=
y ServletContextListener classes you have, and then a generic search=0A> > =
> for putting things into the ServletContext, since that is one of the=0A> =
> > only places that applications typically store long-lived objects.=0A> =
=0A> > Do you have any suggestions for a profiling tool like you described?=
=0A> > Preferably open source.  Thanks.=0A> =0A> Don't know about open sour=
ce products, but I can vouch for YourKit Java=0A> Profiler. As far as I kno=
w, the main difference between YourKit and other=0A> profilers is that Your=
Kit allows you to work through snapshots, whereas=0A> other profilers injec=
t their probes into Java object creation methods.=0A> This means that more =
or less the only moment when YourKit has an effect=0A> on the performance o=
f your application is when you take a memory snapshot.=0A> The other profil=
ers I've seen attempt to trace each object allocation and=0A> deallocation =
in real time, which can be rather CPU consuming (especially=0A> if you're t=
racing a problem you cannot replicate in test environments).=0A> With YourK=
it, you take snapshots of the Java VM memory of your application,=0A> and c=
ompare them "off-line" (i.e. without needing any connection to the=0A> live=
 application).=0A=0A=0A----------------------------------------------------=
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onal commands, e-mail: users-help@tomcat.apache.org=0A=0A=0A      _________=
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