-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 Jerry,
On 12/6/19 01:58, Jerry Malcolm wrote: > Hi Chris, > > See below > > On 12/5/2019 1:07 PM, Christopher Schultz wrote: Jerry, > > On 12/5/19 13:42, Jerry Malcolm wrote: >>>> I'm trying to add some code to monitor my jdbc data >>>> connection pool. > Before you do that, is this a pool that is application-managed? If > Tomcat is managing the connection pool, then none of this is > necessary. If it's application-managed, I'm curious as to why you > are doing that rather than having Tomcat manage it for you. Would > you mind explaining if that's the case? > >> It's tomcat managed. > >> | >> none of this is necessary > >> Are you telling me that it's unnecessary for me to know how many >> connections are currently in use in my connection pool?? Not at all; it's perfectly reasonable to want to know the current stat of affairs. I'm telling you that Tomcat already has a JMX bean that can tell you what you want to know. So you don't have to write any JMX code yourself, other than however you decide to fetch the information from Tomcat. >> I'm trying to determine the high-water mark over several days of >> typical use for how many concurrent connections are in use in >> order to not over-allocate. I'm not 'managing' the connections. >> I'm simply analyzing the usage of the pool. I figured the most >> obvious place to check in-use counts is each time a new >> connection is allocated. Fire up your favorite JMX client (I like VisualVM) and navigate here: /Catalina/DataSource/[host]/[context-path]/javax.sql.DataSource/[datasou rce-name] and look at these attributes: numActive numIdle I think that's everything you already want, right? Also, if you don't want to over-allocate, let the connection pool manage that: maxTotal=20 maxIdle=5 If nobody is using the application, you'll end up with 5 connections in the pool sitting idle after a while. f you have 10 users, presumably, you'll hover at 10 connections bouncing between idle and active for a while. >>>> Each time a connection is requested, I have some jmx code >>>> that logs values from the datasource mbean. > That sounds wasteful. Why not interrogate the connection pool > whenever a client probes the JMX bean? > >> No clue what you mean here. There's no situation where the >> client has any reason to access a jmx bean. I'm using the jmx >> bean to collect and log the current state data for the datasource >> pool each time a connection is requested from the pool. > >> | >> interrogate the connection pool > >> Is there a way to get the jmx data such as in-use connection >> count directly from the jdbc datasource object or some child >> object? I didn't see any methods on the datasource to give me >> that data. That's why I went to jmx to begin with. The thing you are missing is that Tomcat already provides a bean in the JMX tree that contains exactly what you are looking for. It already keeps its stats up-to-date. You ust have to ask it for the current state. From whatever component is interested. If you want realtime stats on exactly when each event occurred -- like an event log -- then you will indeed have to write a bunch of code to do that. But it sounds to me like you are more interested in what I would call "monitoring" than really getting a log of every event. Have a look at slide 16 in this presentation: http://tomcat.apache.org/presentations.html#latest-monitoring-with-jmx > When/how are you binding your bean into the JNDI space? > >> My code was in my original post. Here it is again. You've been around this community long enough to know I'm not a jerk. So stop being a jerk to me. I read your code. I didn't see any object binding. >> I don't know if this the best way. As I said, I found this code >> by googling. It works. But it just dumps every jdbc datasource >> mbean for all different resources without identifying them. I'm >> not creating and binding my own mbeans. I'm simply finding beans >> that already exist. >> >> If there's a way to directly access the bean for a particular >> datasource by name, can you show me the alternate code? > >> MBeanServer server = ManagementFactory.getPlatformMBeanServer(); >> Set<ObjectName> objectNames = server.queryNames(null, null); for >> (ObjectName name : objectNames) { MBeanInfo info = >> server.getMBeanInfo(name); if (info.getClassName().equals( >> "org.apache.tomcat.dbcp.pool2.impl.GenericObjectPool")) { for >> (MBeanAttributeInfo mf : info.getAttributes()) { It's not clear from this code that you are trying to hit a specific bean (because you are hitting them all). It's not clear from this code that you are looking for a container-managed bean versus some other one -- maybe that you registered yourself. It's very easy to look-up a specific bean from the MBeanServer. Are you sure you need to do so? Here's the simple code to do it for an example DataSource like the one in slide 16 of that presentation: MBeanServer server = ManagementFactory.getPlatformMBeanServer(); ObjectName n = new ObjectName("Catalina:type=DataSource,host=localhost,context=/examples,cl ass=javax.sql.DataSource,name="jdbc/MyDataSource"); Object o = server.getAttribute(n, "numActive"); For a DataSource mbean, the "numActive" attribute should be a java.lang.Integer value. Where did I get that magic object name? I used VisualVM to navigate the tree, found the object I was looking for, and copy/pasted the object name directly from there. On the other hand, maybe writing code to inspect the JMX bean isn't what you want to do, either. If you just want to monitor the values, you can use the JMXProxyServlet, which is one of my favorite tools. In that same presentation, starting on page 38, there is information about how to query JMX beans via HTTP from e.g. a monitoring system. I think that might be what you are really looking for. - -chris -----BEGIN PGP SIGNATURE----- Comment: Using GnuPG with Thunderbird - https://www.enigmail.net/ iQIzBAEBCAAdFiEEMmKgYcQvxMe7tcJcHPApP6U8pFgFAl3qcFcACgkQHPApP6U8 pFjUJQ//aZvsVDWC5VoT0zXnU6CLRRrfcMfWaAtjasLbERpS8Ht+OO2RlJulOTcG OuyzjstAGtvjcO/GFgqzYNuOW5oKGHeWyiLPGLhIsk5we74mi7xY7szx4p/Di/3C hFFBashFp2c5t75oc2Eg42L3YRk6jNtug9uvG6YBs5INKlIb1EcARzzR2xmkquvJ /O89kovHLc14y+BXA1e/WNhWsJZPwoRae5g+UpwLFuRqE8SWYQ8EUJ+pm89XaZ6d Hi6DzEfgSwVcMWC5HXe3bEPTJu8YNpepwT7KJXcZfyAjxRnASpnnApjezfJTqqgR NxdXtr/QuRwrFu79HPLOu3XXs2gEuwkm4kXRzdHmEYdJShVh/ls92sII5NkqHCBR 2Xiwowsdd0XkhfmovLLh5dzYoVzWaot1/yLRCGtruLxPQmg+EFZouDPobqknBQZd NtRuAAb64vQob/eQhM5sB3xEJi0NsPRKQZb9n06L4DEgifstLf6pmK9du+vPzxGG fPA9KbdB7VbqgWbbL3ag5zBv03CH6YZkiEPWneulVFiuOC/6LvT2yqXT2Xrv2JUb 1y+50pYLkCcpbfTcxsIcEz1bZNghW+HTJadCeeuM5m76KzhUTy0yewtc22iu+9by RGLg1/cRzS4zg77WhFsOxI77HEN8gInNZPNUhAm30oKWQKRKjSA= =82AW -----END PGP SIGNATURE----- --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
