I am experiencing an issue with delayed writes to the application logs for a Java EE web application running in IBM WebSphere v. 7.x. Logging statements taking up to an hour to appear in the application logs.
The problem doesn't appear related to heavy loads; WAS is responding to page requests almost instantly, and I am testing against a box that isn't used for performance testing, and on a holiday no less -- there is very little activitiy on the server.
My guess would be that the thread associated with logging has been configured with very low priority, but I cant figure out where that would be configured via the admin console or the configuration files.
Has anyone else experienced this sort of issue with WebSphere?
it's possible you don't even enough available threads in the thread pool. Its consistant with the page requests being fast, as they are controlled by the WebContainer threads.
Try increasing it:
Servers > Application Servers > Thread pools > ...
Not sure exactly which one to increase its max value. In worst case, increase'em all. Increase it heavily, so to be sure.
Other options:
make sure you enough disk space / try to connect with jConsole to inquire.
Related
We are working on an ASP.NET 5 Web API project that is in production now but we are experiencing an issue where it becomes unresponsive intermittently throughout the day.
A few notes about the application architecture. It is an ASP.NET Web API project using a MariaDB database on a separate EC2 instance within the same private network. The connection string uses the private IP of the database server to avoid any name resolution issues. The site is hosted via IIS 10.
The application itself has been developed carefully following the best practices provided by Microsoft. Heavy focus on async operations, minimizing query response times and offloading more expensive operations into background services.
The app is extremely responsive. It performs with sub 100ms responses on almost all requests, even the more complicated requests, and all the way up until it becomes unresponsive this high level of performance remains the same. We tend to see between 10-30 requests per second and 300-500 select queries per second at peak usage so not too extreme. However, randomly (2-3 times over a 24 hour period) it will begin hanging on requests and simply not respond to the request. During this time, the database is still extremely responsive and we are never over 300 connections out of our 512 connection limit.
The resources on the application server itself are never really taxed much at all. The CPU never gets above ~20% and the memory usage sits around 20-30%.
If I were to stop the site in IIS and start it again while this is happening, it will quickly come back online. If I don't it will be down for a few minutes until IIS finally kills it due to a failed health check. There are no real errors generated as a response to the issue other than typical errors caused by the hanging of the process such as connection terminated errors. The only thing I have seen before that gave me pause was the fact that there a few connection timeouts when getting the connection from the pool, but like I said, the connections to the server are never close to the limit.
Also, this app and version has been in production for months and it wasn't until the traffic volume started to grow that we started seeing these issues. At this point, I am at a loss for next steps of troubleshooting and I'm seeking suggestions.
In IIS App Pool advanced settings set Start Mode to AlwaysRunning
I never found a root cause for this issue, however, after updating to newer versions of .NET MVC this issue went away. My best guess is that changes with the Kestrel possibly resolved this issue, although, I have no idea what specific change that might have been. I have gone through the change logs a few times and didn't see anything that specifically jumped out at me.
I am currently using a IBM MQ Advanced for Developers server for testing our client and was able to achieve around 1000 messages per second using the sample consumer written in jms, which seems to be pretty slow. Is this a limit for dev server, and if yes that what throughput can be achieved using a licensed production IBM MQ server.
There is no artificial limit associated with IBM MQ Advanced for Developers. It is the same as the licensed production version of IBM MQ.
You don't say what type of machine you were using, what persistence your messages were, what size they were, or any other qualifying criteria.
You say client, but I don't know whether you mean "network attached application" or "driving application". Clearly if your program is running "client-attached" (MQ parlance for network attached), then the network performance will also come into this.
On my Windows laptop, I get 4500 non-persistent msgs/sec, or 2000 persistent msgs/sec using a simple C-language locally bound program. Over client connection (just using localhost, not actually going out over a real network connection) I get 2700 non-persistent msgs/sec, or 1500 persistent msgs/sec.
You should read the MQ Performance Reports for details of the expected rates you can get.
As an ex MQ performance person I would say - it depends.
At one level you can ask - what can one application in isolation process.
For persistent messages this will come down to the rate at which you can write to the log files.
If you have 10 applications in parallel each putting and getting from their own queue, then you will not get 10 times the throughput - you might get 8 or 9 times the throughput.
If they are all processing the same queue, then the throughput may drop a bit more as the queue usage is serialised.
If only one application is writing to the log, the application may see 1 millisecond response time. If you have 10 applications running concurrently, they may see a 3 milliseconds response time - so individual throughput goes down, but with more threads, the overall throughput goes up.
If you have requests coming in over the network, you need to add network time, but you can run more clients and so get improved throughput.
If your application has a delay built in - it may only process a low message rate. You can have lots (1000s) of these and get a high >overall< throughput.
If your application is putting and getting as fast as possible, you may find that you can run 10-100 instances before the throughput plateaus.
Let's say you want to run you box so it is using 75% of the CPU, and the logging is 50% busy.
If you have just MQ on the box, then this can run more messages than if you had DB2 on the box (with DB2 using 50% of the CPU)
If you have an application (DB2) hammering the disk, then the MQ throughput will go down.
If you have lots of applications putting to a server queue - and one server program, you will find the throughput is limited by the rate at which the server can process work. If it is doing DB2 work, it will be slower than no DB2 work. If you find the server queue depth is over 5 then you need more server instances.
As Morag said, see the performance reports, but they are not the clearest reports to understand.
I have a selfhost signalr application, everything is ok but when users become more than 5000, users reconnected rapidly. I know that defalt value of appConcurrentRequestLimit is 5000. and i run this:
cd %windir%\system32\inetsrv
appcmd.exe set config /section:system.webserver/serverRuntime /appConcurrentRequestLimit:100000
but nothing changed. I increased maxConcurrentRequestsPerCPU and requestQueueLimit according to this
but i have got problem yet.
i'm using windows server 2012 and iis 8
You are shooting in the dark here, and you have no data about the actual performance and what's happening. The users could reconnect because of different reasons (server timeouts, regular interval reconnects, server errors). There are countless possibilities.
The correct way to know what's happening and measure performance is to run a Baseline performance load test using the default configuration, and collect the relevant performance counters like current requests, queued requests, current connections, max connections etc.
You should also collect any relevant Error logs on the server that could help you figure out what's happening.
You can find the full list of performance counters you need below:
Memory
.NET CLR Memory# bytes in all Heaps (for w3wp)
ASP.NET
ASP.NET\Requests Current
ASP.NET\Queued
ASP.NET\Rejected
CPU
Processor Information\Processor Time
TCP/IP
TCPv6\Connections Established
TCPv4\Connections Established
Web Service
Web Service\Current Connections
Web Service\Maximum Connections
Threading
.NET CLR LocksAndThreads\ # of current logical Threads
.NET CLR LocksAndThreads\ # of current physical Threads
Once you have your baseline performance results on a graph, then you can modify configuration (e.g. modify the number of concurrent requests like you tried above) and then re-run your test, and collect again the same performance counters.
The performance counter results will speak for themselves, and they will lead you to a solution.
You can generate the load with a tool like Crank:
https://github.com/SignalR/SignalR/tree/dev/src/Microsoft.AspNet.SignalR.Crank
In addition you can also check the SignalR troubleshooting guide:
http://www.asp.net/signalr/overview/testing-and-debugging/troubleshooting
I have an asp.net mvc4 web api interface that gets about 54k requests a day.
http://myserv.x.com/api/123/getstuff?whatstuff=thisstuff
I have 3 web servers behind a load balancer that are setup to handle the http requests.
On average response times are ~300ms. However, lately something has gone awry (or maybe it has always been there) as there is sporadic behavior of response times coming back in 10-20sec. This would be for the same request hitting the same server directly instead of through the load balancer.
GIVEN:
- System has been passed down to me so there may be gaps with IIS confiuration, etc,.
- Database: SQL Server 2008R2
- Web Servers: Windows Server 2008R2 Enterprise SP1
- IIS 7.5
- Using MemoryCache aggressively with Model and Business Objects with eviction set to 2hrs
- Looked at the logs but really don't see anything significantly relevant
- One application pool...no other LOB applications running on this server
Assumptions & Ask:
Somehow I'm thinking that something is recycling the application pool or IIS worker threads are shutting down and restarting thus causing each new request to warmup and recache itself. It's so sporadic that it's tough to trouble shoot right now. The same request to the same server comes back fast as expected (back to back N requests) since it was cached in about 300ms....but wait about 5-10-20min and that same request to the same server takes 16seconds.
I have limited tracing to go by as these are prod systems so I can only expose so much logging details. Any help and information attacking this or similar behavior somebody else has run into is appreciated. Thx
UPDATE:
The w3wpe.exe process grows to ~3G. Somehow it gets wiped out and the PID changes so itself or something is killing it every 3-4min I see tons of warnings in my webserver (IIS) log:
A process serving application pool 'MyApplication' suffered a fatal
communication error with the Windows Process Activation Service. The
process id was '1732'. The data field contains the error number.
After 4-5 days of assessing IIS and configuration vs internal code issues I finally found the issue with little to no help with windbg or debugdiag IIS tools. Those tools contain so much information even with mini dumps or log trace stacks that they can be red herrings. Best bet was to reproduce it by setting up a "copy intelligently" instance of a production system, which we did not have at the time and took a bit for ops to set something up.
Needless to say the problem had to do with over cacheing business objects. There was one race condition where updates on a certain table were updating an attribute to that corresponding business object (updates were coming from multiple servers) which was causing an OOC stackoverflow that pretty much caused the cacheing to recursively cache itself to death thus causing the w3wp.exe process to die and psuedo-recycle itself. It was one of those edge cases that was incredibly hard to test and repro in a non-production environment.
I implemented a web application to start the Tomcat service works very quickly, but spending hours and when more users are entering is getting slow (up to 15 users approx.).
Checking RAM usage statistics (20%), CPU (25%)
Server Features:
RAM 8GB
Processor i7
Windows Server 2008 64bit
Tomcat 7
MySql 5.0
Struts2
-Xms1024m
-Xmx1024m
PermGen = 1024
MaxPernGen = 1024
I do not use Web server, we publish directly on Tomcat.
Entering midnight slowness is still maintained (only 1 user online)
The solution I have is to restart the Tomcat service and response time is again excellent.
Is there anyone who has experienced this issue? Any clue would be appreciated.
Not enough details provided. Need more information :(
Use htop or top to find memory and CPU usage per process & per thread.
CPU
A constant 25% CPU usage in a 4 cores system can indicate that a single-core application/thread is running 100% CPU on the only core it is able to use.
Which application is eating the CPU ?
Memory
20% memory is ~1.6GB. It is a bit more than I expect for an idle server running only tomcat + mysql. The -Xms1024 tells tomcat to preallocate 1GB memory so that explains it.
Change tomcat settings to -Xms512 and -Xmx2048. Watch tomcat memory usage while you throw some users at it. If it keeps growing until it reaches 2GB... then freezes, that can indicate a memory leak.
Disk
Use df -h to check disk usage. A full partition can make the issues you are experiencing.
Filesystem Size Used Avail Usage% Mounted on
/cygdrive/c 149G 149G 414M 100% /
(If you just discovered in this example that my laptop is running out of space. You're doing it right :D)
Logs
Logs are awesome. Yet they have a bad habit to fill up the disk. Check logs disk usage. Are logs being written/erased/rotated properly when new users connect ? Does erasing logs fix the issue ? (copy them somewhere for future analysis before you erase them)
If not. Logs are STILL awesome. They have the good habit to help you track bugs. Check tomcat logs. You may want to set logging level to debug. What happens last when the website die ? Any useful error message ? Do user connections are still received and accepted by tomcat ?
Application
I suppose that the 25% CPU goes to tomcat (and not mysql). Tomcat doesn't fail by itself. The application running on it must be failing. Try removing the application from tomcat (you can eventually put an hello world instead). Can tomcat keep working overnight without your application ? It probably can, in which case the fault is on the application.
Enable full debug logging in your application and try to track the issue. Run it straight from eclipse in debug mode and throw users at it. Does it fail consistently in the same way ?
If yes, hit "pause" in the eclipse debugger and check what the application is doing. Look at the piece of code each thread is currently running + its call stack. Repeat that a few times. If there is a deadlock, an infinite loop, or similar, you can find it this way.
You will have found the issue by now if you are lucky. If not, you're unfortunate and it's a tricky bug that might be deep inside the application. That can get tricky to trace. Determination will lead to success. Good luck =)
For performance related issue, we need to follow the given rules:
You can equalize and emphasize the size of xms and xmx for effectiveness.
-Xms2048m
-Xmx2048m
You can also enable the PermGen to be garbage collected.
-XX:+UseConcMarkSweepGC -XX:+CMSPermGenSweepingEnabled -XX:+CMSClassUnloadingEnabled
If the page changes too frequently to make this option logical, try temporarily caching the dynamic content, so that it doesn't need to be regenerated over and over again. Any techniques you can use to cache work that's already been done instead of doing it again should be used - this is the key to achieving the best Tomcat performance.
If there any database related issue, then can follow sql query perfomance tuning
rotating the Catalina.out log file, without restarting Tomcat.
In details,There are two ways.
The first, which is more direct, is that you can rotate Catalina.out by adding a simple pipe to the log rotation tool of your choice in Catalina's startup shell script. This will look something like:
"$CATALINA_BASE"/logs/catalina.out WeaponOfChoice 2>&1 &
Simply replace "WeaponOfChoice" with your favorite log rotation tool.
The second way is less direct, but ultimately better. The best way to handle the rotation of Catalina.out is to make sure it never needs to rotate. Simply set the "swallowOutput" property to true for all Contexts in "server.xml".
This will route System.err and System.out to whatever Logging implementation you have configured, or JULI, if you haven't configured.
See more at: Tomcat Catalina Out
I experienced a very slow stock Tomcat dashboard on a clean Centos7 install and found the following cause and solution:
Slow start up times for Tomcat are often related to Java's
SecureRandom implementation. By default, it uses /dev/random as an
entropy source. This can be slow as it uses system events to gather
entropy (e.g. disk reads, key presses, etc). As the urandom manpage
states:
When the entropy pool is empty, reads from /dev/random will block until additional environmental noise is gathered.
Source: https://www.digitalocean.com/community/questions/tomcat-8-5-9-restart-is-really-slow-on-my-centos-7-2-droplet
Fix it by adding the following configuration option to your tomcat.conf or (preferred) a custom file into /tomcat/conf/conf.d/:
JAVA_OPTS="-Djava.security.egd=file:/dev/./urandom"
We encountered a similar problem, the cause was "catalina.out". It is the standard destination log file for "System.out" and "System.err". It's size kept on increasing thus slowing things down and ultimately tomcat crashed. This problem was solved by rotating "catalina.out". We were using redhat so we made a shell script to rotate "catalina.out".
Here are some links:-
Mulesoft article on catalina (also contains two methods of rotating):
Tomcat Catalina Introduction
If "catalina.out" is not the problem then try this instead:-
Mulesoft article on optimizing tomcat:
Tuning Tomcat Performance For Optimum Speed
We had a problem, which looks similar to yours. Tomcat was slow to respond, but access log showed just milliseconds for answer. The problem was streaming responses. One of our services returned real-time data that user could subscribe to. EPOLL were becoming bloated. Network requests couldn't get to the Tomcat. And whats more interesting, CPU was mostly idle (since no one could ask server to do anything) and acceptor/poller threads were sitting in WAIT, not RUNNING or IN_NATIVE.
At the time we just limited amount of such requests and everything became normal.