A huge webapp in my Tomcat sometimes starts using too many DBCP connections, leading to problems.
To investigate, I want to know precisely at each point in time what thread/method is holding a connection of the pool. Does not need to be real-time, post-mortem analysis is OK.
I have been looking for such a DBCP monitoring tool, in vain, so I am about to write mine.
(if there is any interest I can make it open source)
Here is my plan:
Modify PoolingDataSource.getConnection to log "DBCP+1 <thread-id>"
Modify DelegatingConnection.close to log "DBCP-1 <thread-id>"
Write a small script to generate this simple CSV for visualization:
QUESTION:
Am I missing some Commons-DBCP 1.4 concept that makes the idea invalid?
Or am I re-inventing the wheel?
There was no such tool, so I created it:
https://github.com/nicolas-raoul/Commons-DBCP-monitoring
It monitors Commons DBCP usage (using/waiting for connection) and allows one to create such graphs:
I asked whether my assumptions are valid on the Commons DBCP mailing list.
Related
I have a Dropwizard application I am working with where I need to be able to monitor for active HTTP connections. I know Metrics provides classes for Instrumenting Jetty, and of interest to me is measuring total number of active connections....however the javadoc doesn't help me much, and I can't find any examples of how this specific functionality is implemented. Does anyone have any examples they can share?
I'm not sure what your exact use-case is but if you just need to be able to see active connections I think the simplest solutions are just using monitoring solutions like JMX, Datadog, New Relic, or Appdynamics. If you need it in the code I think you'd need to manually implement something. I'd recommend StatsD or Redis is that's the path you go down.
How do you isolate a performance issue to a specific component of the application infrastructure? Specifically, are there distinct markers in the result logs that distinguish between bottlenecks at web, application and/or database server levels?
I was asked this question in an interview and went blank on it. Seems this information is not available anywhere.
In addition to SiteScope and other agentless monitoring of system components, you need to make sure your scenario and scripts are working as expected. This includes proper error checking and use of transactions (and a host of other things). If the transactions are granular enough, this will give you insight into at least the requests that have performance issues. Once you have these indicators, work with the infrastructure team to review logs and other information. Being an iterative process, tests can be made to focus on a smaller and smaller section of the infrastructure.
In addition, loadrunner scripts don't have to be made strictly 'coming in through the frontdoor'. If you have a multi-tiered system, scripts can be made to hit the web/app/database servers directly.
For what to look for, focus on any measurements that have 'knees' or 'hockey stick' type of behaviour. You can hook into any of the server resource type measurements directly in the controller and integrate other team's stats in the analysis phase. Compare with benchmarks at lower virtual user levels to determine what is acceptable and unacceptable.
Good luck!
If the interview is focused on LoadRunner and SiteScope is considered - I'd come to conclusion that it's more focused on HP/Mercury solutions.. In that case I'd suggest you to look into HP Diagnostics and it's LoadRunner integration capabilities.
This type of information is usually not available by just looking at the standard results from a performance test.
Parts of the information you are looking for MAY be found by using SiteScope to monitor all the relevant servers in the test. SiteScope offers many counters to look at such as CPU, Memory, Disk I/O and Network I/O - as seen on each server.
This information perhaps gives clues as to where the bottleneck is, and the more counters you add to SiteScope, the bigger the change to pinpoint the bottleneck.
It is a very common misconception that AppServer and DBServer bottlenecks could be identified by just looking at the raw response times or hits, pages etc (web protocol), unless of course the URI accessed defines the exact component(s) in the system...
Is there an application that is capable of monitoring AND logging information (to file) about another process (in particular IIS aspnet_wp.exe) like (in periods of time):
- memory usage of process
- cpu usage
Or maybe there is another way to monitor IIS process?
Thanks Pawel
You can check Process Monitor from Microsoft.
Process Monitor is an advanced
monitoring tool for Windows that shows
real-time file system, Registry and
process/thread activity. It combines
the features of two legacy
Sysinternals utilities, Filemon and
Regmon, and adds an extensive list of
enhancements including rich and
non-destructive filtering,
comprehensive event properties such
session IDs and user names, reliable
process information, full thread
stacks with integrated symbol support
for each operation, simultaneous
logging to a file, and much more.
One choice would be Process explorer http://technet.microsoft.com/en-us/sysinternals/bb896653.aspx
You might want to look at the ANTS Performance and Memory Profilers from Red Gate. I'm using their memory profiler to track down some memory issues as I write this.
Pretty much any monitoring system or framework that allows custom checks is capable of this.
You write your check and just put an extra line in it to post/print/put something to a file of your choice.
I for example use sensu for which I wright custom checks in ruby.
So I can easily do something like
if %x[{ping]}
ok
%x[{ print ‘all is well’ > syslog]}
end
and similar to that you can do for most other monitoring systems like Nagios etc.
What, at a minimum, should an application health-monitoring system do for you (the developer) and/or your boss (the IT Manager) and/or the operations (on-call) staff?
What else should it do above the minimum requirements?
Is monitoring the 'infrastructure' applications (ms-exchange, apache, etc.) sufficient or do individual user applications, web sites, and databases also need to be monitored?
if the latter, what do you need to know about them?
ADDENDUM: thanks for the input, i was really looking for application-level monitoring not infrastructure monitoring, but it is good to know about both
Whether the application is running.
Unusual cpu/memory/network usage.
Report any unhandled exceptions.
Status of various modules (if applicable).
Status of external components (databases, webservices, fileservers, etc.)
Number of pending background tasks (if applicable).
Maybe track usage of the application and report statistics on most/less used functionalities so you know where optimizations are most beneficial.
The answer is 'it depends'. Why do you need to monitor? How large is your operations staff? Do you need reporting? What is the application environment? Who cares if the application fails? Who cares if an exception happens? Are any of the errors recoverable? I could ask questions like these for a long time.
Great question.
We've been looking for some application-level monitoring solution for our needs some time ago without any luck. Popular monitoring solution are mostly addressed to monitor infrastrcture and - in my opinion - they are too complicated for a requirements of most of small and mid-sized companies.
We required (mainly) following features:
alerts - we wanted to know about
incident as fast as possible
painless management - hosted service wouldbe
the best
visualizations - it's good to know what is going on and take some knowledge from the data
Because we didn't find suitable solution we started to write our own. Finally we've ended with up-and-running service called AlertGrid. (You can check it for free of course.)
The idea behind it is to provide an easy way to handle custom monitoring scenarios. Integration API is very simple (one function with two required parameters). At the momment we and others are using it for:
monitor scheduled tasks (cron jobs)
monitor entire application logic execution
alert on errors in applications
we are also working on examples of basic infrastructure monitoring using AlertGrid
This is such an open ended question, but I would start with physical measurements.
1. Are all the machines I think are hosting this site pingable?
2. Are all the machines which should be serving content actually serving some content? (Ideally this would be hit from an external network.)
3. Is each expected service on each machine running?
3a. Have those services run recently?
4. Does each machine have hard drive space left? (Don't forget the db)
5. Have these machines been backed up? When was the last time?
Once one lays out the physical monitoring of the systems, one can address those specific to a system?
1. Can an automated script log in? How long did it take?
2. How many users are live? Have there been a million fake accounts added?
...
These sorts of questions get more nebulous, and can be very system specific. They also usually can be derived reactively when responding to phsyical measurements. Hard drive fill up, maybe the web server logs got filled up because a bunch of agents created too many fake users. That kind of thing.
While plan A shouldn't necessarily be reactive, it is the way many a site setup a monitoring system.
Minimum: make sure it is running :)
However, some other stuff would be very useful. For example, the CPU load, RAM usage and (in multiuser systems) which user is running what. Also, for applications that access network, a list of network connections for each app. And (if you have access to client computer(s)) it would be cool to be able to see the 'window title' of the app - maybe check each 2-3 minutes if it changed and save it. Also, a list of files open by the application could be very useful, but it is not a must.
I think this is fairly simple - monitor so that you can be warned early enough before something goes wrong. That means monitor dependencies and the application itself.
It's really hard to provide specifics if you're not going to give details on the application you're monitoring, so I'd say use that as a general rule.
At a minimum you want to know that the system is healthy. This is subjective in what defines your system is healthy. Is it computers are up, the needed resources exist, the data is flowing through the system, the data is properly producing results, etc, etc.
In my project we do monitoring of most of this and then some. It really comes down to what is the highest level that you can use to analyze that everything is working. In our case we need to know down to the data output. If you just need to know down to the are these machines up it saves you on trying to show an inexperienced end user what is wrong.
There are also "off the shelf" tools that will do a lot of the hard work for you if you are just looking too hard into data results. I particularly liked Nagios when I was looking around but we needed more than it could easily show so I wrote our own monitoring system. Basically we also watch for "peculiarities" in the system, memory / cpu spikes, etc...
thanks everyone for the input, i was really looking for application-level monitoring not infrastructure monitoring, but it is good to know about both
the difference is:
infrastructure monitoring would be servers plus MS Exchange Server, Apache, IIS, and so forth
application monitoring would be user machines and the specific programs that they use to do their jobs, and/or servers plus the data-moving/backend applications that they run to keep the data flowing
sometimes it's hard to draw the line - an oversimplified definition might be "if your team wrote it, it's an application; if you bought it, it's infrastructure"
i think in practice it is best to monitor both
What you need to do is to break down the business process of the application and then have the software emit events at major business components. In addition, you'll need to create end to end synthetic transactions (eg. emulating end users clicking on a website). All that data would be fed into an monitoring tool. In the past, I've done JMX for applications of which flowed into Tivoli Monitoring's JMX Adapter and then I've done scripts that implement a "fake user" and then pipe in the results into Tivoli Monitoring's Script Adapter. Tivoli Monitoring takes the data and then creates application health and performance charts from that raw data.
By looking at our DB's error log, we found that there was a constant stream of almost successful SQL injection attacks. Some quick coding avoided that, but how could I have setup a monitor for both the DB and Web server (including POST requests) to check for this? By this I mean if there are off the shelf tools for script-kiddies, are there off the shelf tools that will alert you to their sudden random interest in your site?
Funnily enough, Scott Hanselman had a post on UrlScan today which is one thing you could do to help monitor and minimize potential threats. It's a pretty interesting read.
UrlScan does seem like a nice option for iis6 and 7; I also found: dotDefender for pay which also covers Apache or IIS 5-7, and I had found an SQL Injection sanitation ISAPI
It is also worth noting in light of a recent wide spread SQL Injection attempt that dissallowing your webapp's db user account from querying the system tables (in MS SQL Server it's sysobjects and syscolumns) is a good idea.
I think this thread warrants more free solutions for Apache and other web servers.
Unfortunately intrusion detection was not what I had in mind, so sgfree isn't exactly a web site attack monitor, unless I'm not understanding how it works.
If you could go back and modify your app code, I'd suggest getting log4j/log4net integrated into the application. From there you could write code that would check a form field or URL (say at the global.asax level for .NET apps) and make a log entry when malicious code is detected.
The nice thing about log4j/log4net is that you can configure an e-mail/pager/SMS type appender so as soon as the malicious attempt was caught, you would be notified.
I'm in the process of merging some log4net code into our CMS system we have and I'm looking to do just this in light of the influx of ASPRox attacks that have been coming our way.
Monitoring web and DB access logs should alert you to things like this, but if you want a more fully featured alert system I would suggest some kind of IDS/IPS. You'll need a spare machine though, and a switch that can do port mirroring.
If you have those then an IDS is a cheap way of monitoring your traffic for many intrusion attempts (there will be lots). Snort (www.snort.org) based IDSes are excellent, and there are some free fully packaged versions available. One I have used is StrataGuard (http://sgfree.stillsecure.com/), and it can be configured as an IDS (Intrusion Detection System) or as an IPS (Intrusion Prevention System). It's free to use if your traffic does not exceed 5Mbps.
If you do go with an IDS/IPS I'd advise you to let it run as a simple IDS for a month or so, before you allow it to prevent attacks.
This may be overkill, but if you have a spare machine lying around it can't hurt to have an IDS running passively.
You can set up your system to kick out some error message that then makes a JSON or http call to a system that will monitor, report (log) and send out any kind of alert such as SMS/email or a phone call.
Check out developer.alertcaster.com
Especially if you need to monitor multiple simultaneous events, which it sounds like you have going on, this might be a good fix.