Re: tomcat 8.5.23 dbcp not honoring autocommit = false?
On Thu, Oct 26, 2017 at 3:00 PM, Christopher Schultzwrote: > -BEGIN PGP SIGNED MESSAGE- > Hash: SHA256 > > Chris, > > On 10/16/17 9:43 AM, Chris Cheshire wrote: >> On Fri, Oct 13, 2017 at 5:00 PM, Christopher Schultz >> wrote: >>> -BEGIN PGP SIGNED MESSAGE- >> >>> When you say you have "autocommit disabled in mysql config" what >>> do you mean? >>> >> >> /etc/my.cnf : [mysqld] autocommit=0 >> >> This turns off autocommit off as a default for all connections. > > It only affects connections from MySQL's "mysql" command-line client. > It does not affect e.g. Java-based clients. > It's in the [mysqld] section of my.cnf so it is supposed to be at a server level. I do have stuff in the [mysql] section that affects the command line client behaviour only. >> I need this at a minimum for the mysql client, but in the absence >> of any other configuration it should be the default for a >> connection from any client. > > The JDBC spec says that all connections are auto-commit unless > otherwise specified. So if you are creating your own connections or > using e.g. a connection-pool then you'll have to make sure that you > configure them to be NOT auto-commit. This is not a setting that you > can control from the server. > > More below. > I was doing that anyway in both the pool configuration and when the connection is grabbed from the pool. I've since changed the code to not touch the autocommit setting and leave that up to the datasource (resource config in context.xml) >>> On 10/13/17 10:17 AM, Chris Cheshire wrote: As a further test I just took out my explicit rollback in my DAOFactory close() method, and swapped back to commons dbcp. Added an update that wasn't explicitly committed, and it correctly did not get committed when the connection was closed. Swapped back to tomcat dbcp and repeated, it got committed without an explicit commit statement. I'm really puzzled as to why *I* have to explicitly rollback on close if autocommit is not enabled, instead of tomcat dbcp handling that when commons dbcp appears to do it. >>> >>> No connection pool can read your mind. If you begin a transaction >>> (or never start one), you must either commit or rollback. Merely >>> calling close() does not explicitly cause either of those to be >>> called. >>> >> >> And that's just it. If I don't explicitly commit, then why are >> changes being committed when the connection is closed and returned >> back to the pool? >> If I do daoFactory = new MySQLDAOFactoryImpl(getDataSource()); // update #1 daoFactory.commit() // update #2 daoFactory.close(); then update #2 is being committed. >>> >>> I'm curious why you are doing "update #2" without either COMMIT >>> or ROLLBACK. That seems like ... a mistake. >>> >> >> Correct. This is an example to illustrate a mistake I found in my >> code. I found a servlet that actually wasn't explicitly committing >> when it should have been, yet everything it was doing was being >> committed to the database. >> >>> - From the Connection.close() javadoc: >>> >>> " It is strongly recommended that an application explicitly >>> commits or rolls back an active transaction prior to calling the >>> close method. If the close method is called and there is an >>> active transaction, the results are implementation-defined. " >>> >> >> If a commit is not being explicitly issued, then the commit >> behaviour should honor that of the connection, yes? > > Yes, but it's more complicated than that. Any change to the > connection's settings (which happen ALL THE TIME when the connection > is being returned to a connection pool) will cause an implicit COMMIT. > That's why it's super important for you to either COMMIT or ROLLBACK > yourself. > > Note that "autocommit = false" doesn't mean "autorollback=true". > Best-case scenario for you there is that the transaction gets > committed *later* when another piece of your code grabs a connection > from the pool, does its work (successfully) and issues a COMMIT. > > It's just NOT the pool's job nor the driver's job to clean-up after > any messes created by your code. Agreed, however since it was acting differently than the commons pool I mistakenly attributed the behaviour to tomcat jdbc instead. > >>> There *is* an implicit COMMIT executed if the autocommit flag is >>> flipped for any reason, either true->false or false->true. >>> >>> If you have autocommit=false in your configuration >>> (which you do), then calling setAutoCommit(false) shouldn't do >>> anything. >>> If I put in this in the close() method of my DAO Factory if (!this.dbConn.getAutoCommit()) { this.dbConn.rollback(); } before the close() call, then update #2 is correctly not getting committed. >>> >>> This is probably the wrong approach: your close() method doesn't >>> know whether it's
Re: tomcat 8.5.23 dbcp not honoring autocommit = false?
-BEGIN PGP SIGNED MESSAGE- Hash: SHA256 Chris and Keiichi, On 10/17/17 5:31 PM, Chris Cheshire wrote: > On Tue, Oct 17, 2017 at 3:44 AM, Keiichi Fujino >wrote: >> Hi >> >> You have set >> factory="org.apache.tomcat.jdbc.pool.DataSourceFactory". In other >> words, you do not use (tomcat)DBCP, you are using Tomcat >> jdbc-pool. > > That's what I meant sorry. Was comparing to commons-dbcp and went > dyslexic on the acronyms. > >> >> In DBCP, the default of rollbackOnReturn attribute is true. >> However, in Tomcat jdbc-pool, the default of rollbackOnReturn( >> and commitOnReturn ) attribute are false. >> >> see: >> http://commons.apache.org/proper/commons-dbcp/configuration.html >> http://tomcat.apache.org/tomcat-8.5-doc/jdbc-pool.html >> >> > > Now that explains it entirely. Thank you so much! > > Part of this is me failing to RTFM entirely, and then part is the > nature of configuration references - if you don't know what you are > looking for it is easy to miss important details. It would be > helpful if that page explained some of the fundamental differences > from a usage perspective (not just implementation improvements) but > that's another story. I didn't realize that these two libraries had different default semantics. IMO, Tomcat's jdbc-pool behaves _correctly_ in that it doesn't issue an unnecessary ROLLBACK on every connection returned to the pool. - -chris -BEGIN PGP SIGNATURE- Comment: GPGTools - http://gpgtools.org Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQJRBAEBCAA7FiEEMmKgYcQvxMe7tcJcHPApP6U8pFgFAlnyMUcdHGNocmlzQGNo cmlzdG9waGVyc2NodWx0ei5uZXQACgkQHPApP6U8pFij4w//Q5tGBgwdcXsT9k/V Raop4RalDLSeJNhTDY2FIMpDNHnvcq45BrOqkO3GhukyuNxpn/aJrUsE6ucbXN/3 jeb32JDEJ5f8FK5A6t9ZCeEG84p5BNDEfQUJEJQA5G67tBrhYzGfbW0t4X4qMyuM l/xrVBLVP9JCLdjWUg/VnTyYhNKZGkIHYXzX5QtmZtjTRH+OBzCTuTT4B54WhkWM MIFn5WYXxOnP6/+nR4f4rcV8VPKiJOoYuTv+dxt/Ih4IiGPNh+xUIzNS+lCTiagK rsWDq51pqkH05nHdJTZ2+aZJEs/mFWXaCyjU3BOvIEPaUKaBJgjxjGBrIL1Tb/a9 jVEU3WrRJ3jNSNGYeN9kBfaL2dtB4W/H1btk1WAu39IuAdD/ZEcr8VgyIbteP6ar StHXm2g5xt88X8ndgIo/2jdZisZ8LBNFksZ5yMXRuJckw3FN/YeLzHbe3gbPFXtv K4xMFlI8OZFqr89EuNzzQjsris0gy6k3EFfQGz5tJDK7yiTNIEBfQbjGj9eFyYoA 7V2f7HvUIVmiNnRpCdg0CihdOypzIrXAZePOYTJGzkER0pUlGqt4ue4+6o5i8GSf lap1sScK7Q6FiOGAvtQ3ZE+WMXvUFqGrs//O0pIi67KwXXHu+WsDV7av1BupZ0/F hFkomQ3hHYAJoDoEJJHkn7jRXpY= =zG27 -END PGP SIGNATURE- - To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
Re: tomcat 8.5.23 dbcp not honoring autocommit = false?
-BEGIN PGP SIGNED MESSAGE- Hash: SHA256 Chris, On 10/16/17 9:43 AM, Chris Cheshire wrote: > On Fri, Oct 13, 2017 at 5:00 PM, Christopher Schultz >wrote: >> -BEGIN PGP SIGNED MESSAGE- > >> When you say you have "autocommit disabled in mysql config" what >> do you mean? >> > > /etc/my.cnf : [mysqld] autocommit=0 > > This turns off autocommit off as a default for all connections. It only affects connections from MySQL's "mysql" command-line client. It does not affect e.g. Java-based clients. > I need this at a minimum for the mysql client, but in the absence > of any other configuration it should be the default for a > connection from any client. The JDBC spec says that all connections are auto-commit unless otherwise specified. So if you are creating your own connections or using e.g. a connection-pool then you'll have to make sure that you configure them to be NOT auto-commit. This is not a setting that you can control from the server. More below. >> On 10/13/17 10:17 AM, Chris Cheshire wrote: >>> >>> >>> As a further test I just took out my explicit rollback in my >>> DAOFactory close() method, and swapped back to commons dbcp. >>> Added an update that wasn't explicitly committed, and it >>> correctly did not get committed when the connection was closed. >>> Swapped back to tomcat dbcp and repeated, it got committed >>> without an explicit commit statement. >>> >>> I'm really puzzled as to why *I* have to explicitly rollback >>> on close if autocommit is not enabled, instead of tomcat dbcp >>> handling that when commons dbcp appears to do it. >> >> No connection pool can read your mind. If you begin a transaction >> (or never start one), you must either commit or rollback. Merely >> calling close() does not explicitly cause either of those to be >> called. >> > > And that's just it. If I don't explicitly commit, then why are > changes being committed when the connection is closed and returned > back to the pool? > >>> If I do >>> >>> daoFactory = new MySQLDAOFactoryImpl(getDataSource()); >>> >>> // update #1 daoFactory.commit() >>> >>> // update #2 daoFactory.close(); >>> >>> then update #2 is being committed. >> >> I'm curious why you are doing "update #2" without either COMMIT >> or ROLLBACK. That seems like ... a mistake. >> > > Correct. This is an example to illustrate a mistake I found in my > code. I found a servlet that actually wasn't explicitly committing > when it should have been, yet everything it was doing was being > committed to the database. > >> - From the Connection.close() javadoc: >> >> " It is strongly recommended that an application explicitly >> commits or rolls back an active transaction prior to calling the >> close method. If the close method is called and there is an >> active transaction, the results are implementation-defined. " >> > > If a commit is not being explicitly issued, then the commit > behaviour should honor that of the connection, yes? Yes, but it's more complicated than that. Any change to the connection's settings (which happen ALL THE TIME when the connection is being returned to a connection pool) will cause an implicit COMMIT. That's why it's super important for you to either COMMIT or ROLLBACK yourself. Note that "autocommit = false" doesn't mean "autorollback=true". Best-case scenario for you there is that the transaction gets committed *later* when another piece of your code grabs a connection from the pool, does its work (successfully) and issues a COMMIT. It's just NOT the pool's job nor the driver's job to clean-up after any messes created by your code. >> There *is* an implicit COMMIT executed if the autocommit flag is >> flipped for any reason, either true->false or false->true. >> >> If you have autocommit=false in your configuration >> (which you do), then calling setAutoCommit(false) shouldn't do >> anything. >> >>> If I put in this in the close() method of my DAO Factory >>> >>> if (!this.dbConn.getAutoCommit()) { this.dbConn.rollback(); } >>> >>> before the close() call, then update #2 is correctly not >>> getting committed. >> >> This is probably the wrong approach: your close() method doesn't >> know whether it's better to call commit() or rollback(), so it >> should do neither. > > I realise this too, however I have to have it in otherwise if an > exception is thrown, then work is being committed regardless of the > fact that I have autocommit turned OFF in 3 levels, all the way > back to the mysqld configuration. The mysqld configuration is not relevant, here. Are you able to run your code through a debugger to see when the COMMIT is happening? > This behaviour does not happen with commons dbcp, only tomcat dbcp. > There is a difference in default behaviour between the two pools > when a transaction is not explicitly committed or rolled back when > a connection is closed and returned to the pool. Can you create a SSCCE test-case which demonstrates
Re: tomcat 8.5.23 dbcp not honoring autocommit = false?
On Tue, Oct 17, 2017 at 3:44 AM, Keiichi Fujinowrote: > Hi > > You have set factory="org.apache.tomcat.jdbc.pool.DataSourceFactory". > In other words, you do not use (tomcat)DBCP, you are using Tomcat jdbc-pool. That's what I meant sorry. Was comparing to commons-dbcp and went dyslexic on the acronyms. > > In DBCP, the default of rollbackOnReturn attribute is true. > However, in Tomcat jdbc-pool, the default of rollbackOnReturn( and > commitOnReturn > ) attribute are false. > > see: > http://commons.apache.org/proper/commons-dbcp/configuration.html > http://tomcat.apache.org/tomcat-8.5-doc/jdbc-pool.html > > Now that explains it entirely. Thank you so much! Part of this is me failing to RTFM entirely, and then part is the nature of configuration references - if you don't know what you are looking for it is easy to miss important details. It would be helpful if that page explained some of the fundamental differences from a usage perspective (not just implementation improvements) but that's another story. Cheers, Chris - To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
Re: tomcat 8.5.23 dbcp not honoring autocommit = false?
Hi You have set factory="org.apache.tomcat.jdbc.pool.DataSourceFactory". In other words, you do not use (tomcat)DBCP, you are using Tomcat jdbc-pool. In DBCP, the default of rollbackOnReturn attribute is true. However, in Tomcat jdbc-pool, the default of rollbackOnReturn( and commitOnReturn ) attribute are false. see: http://commons.apache.org/proper/commons-dbcp/configuration.html http://tomcat.apache.org/tomcat-8.5-doc/jdbc-pool.html 2017-10-12 6:21 GMT+09:00 Chris Cheshire: > Working on a migration from 7 to 8.5, and in it I am now using the > tomcat dbcp, instead of apache commons dbcp. I have found that with no > other changes to the db code (except the factory param for the > resource), it is working fine other than there is an implicit commit > happening when I close a connection, even with autocommit turned off > in mysql config, resource config AND in my code. > > Resource config : > >auth="Container" > type="javax.sql.DataSource" > driverClassName="com.mysql.jdbc.Driver" > url="jdbc:mysql://localhost:3306/mydb?useUnicode=true > characterEncoding=utf8useSSL=false" > factory="org.apache.tomcat.jdbc.pool.DataSourceFactory" > username="" > password="" > maxActive="150" > maxIdle="25" > maxWait="6" > removeAbandoned="true" > removeAbandonedTimeout="300" > logAbandoned="true" > validationQuery="/* ping */" > testOnBorrow="true" > testWhileIdle="true" > timeBetweenEvictionRunsMillis="60" > defaultAutoCommit="false" /> > > Only thing changed in that from 7.x to 8.5.x is the factory was > org.apache.commons.dbcp.BasicDataSourceFactory. I am using Connector/J > 5.1.44 (latest version). > > > Getting a connection boils down to this in my code (pieces pulled out > of factories and other classes) > > (Support class in web code) > public static DataSource getDataSource() { > try { > return (DataSource)new > InitialContext().lookup("java:comp/env/" + > ServletContextParameters.getDatabaseResourceName()); > } > catch (NamingException ex) { > throw new RuntimeException("unable to find datasource", ex); > } > } > > > (DAO Factory implementation) > public MySQLDAOFactoryImpl(@NotNull DataSource dataSource) { > this.dataSource = dataSource; > > try { > this.dbConn = this.dataSource.getConnection(); > this.dbConn.setAutoCommit(false); > this.dbConn.setTransactionIsolation(Connection.TRANSACTION_READ_ > COMMITTED); > } > catch (SQLException ex) { > throw new DAOException("unable to get database connection", ex); > } > } > > @Override > public void close() { > try { > if (this.dbConn != null) { > this.dbConn.close(); > } > } > catch (SQLException ex) { > throw new DAOException("error closing database connection", ex); > } > } > > > If I do > > daoFactory = new MySQLDAOFactoryImpl(getDataSource()); > > // update #1 > daoFactory.commit() > > // update #2 > daoFactory.close(); > > then update #2 is being committed. > > If I put in this in the close() method of my DAO Factory > > if (!this.dbConn.getAutoCommit()) { > this.dbConn.rollback(); > } > > before the close() call, then update #2 is correctly not getting committed. > > I looked back through the recent tomcat changelogs, and found a > reference to https://bz.apache.org/bugzilla/show_bug.cgi?id=61425 > under the 8.5.21 release which looks like it might be addressing this > problem. However, when I download the source for 8.5.23, there is no > org.apache.tomcat.jdbc directory so I can't dive in there. > > Anyone else experienced this? Hopefully I am just missing something > obvious. > > - > To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org > For additional commands, e-mail: users-h...@tomcat.apache.org > > -- > Keiichi.Fujino >
Re: tomcat 8.5.23 dbcp not honoring autocommit = false?
On Fri, Oct 13, 2017 at 5:00 PM, Christopher Schultzwrote: > -BEGIN PGP SIGNED MESSAGE- > When you say you have "autocommit disabled in mysql config" what do > you mean? > /etc/my.cnf : [mysqld] autocommit=0 This turns off autocommit off as a default for all connections. I need this at a minimum for the mysql client, but in the absence of any other configuration it should be the default for a connection from any client. > On 10/13/17 10:17 AM, Chris Cheshire wrote: >> >> >> As a further test I just took out my explicit rollback in my >> DAOFactory close() method, and swapped back to commons dbcp. Added >> an update that wasn't explicitly committed, and it correctly did >> not get committed when the connection was closed. Swapped back to >> tomcat dbcp and repeated, it got committed without an explicit >> commit statement. >> >> I'm really puzzled as to why *I* have to explicitly rollback on >> close if autocommit is not enabled, instead of tomcat dbcp handling >> that when commons dbcp appears to do it. > > No connection pool can read your mind. If you begin a transaction (or > never start one), you must either commit or rollback. Merely calling > close() does not explicitly cause either of those to be called. > And that's just it. If I don't explicitly commit, then why are changes being committed when the connection is closed and returned back to the pool? >> If I do >> >> daoFactory = new MySQLDAOFactoryImpl(getDataSource()); >> >> // update #1 daoFactory.commit() >> >> // update #2 daoFactory.close(); >> >> then update #2 is being committed. > > I'm curious why you are doing "update #2" without either COMMIT or > ROLLBACK. That seems like ... a mistake. > Correct. This is an example to illustrate a mistake I found in my code. I found a servlet that actually wasn't explicitly committing when it should have been, yet everything it was doing was being committed to the database. > - From the Connection.close() javadoc: > > " > It is strongly recommended that an application explicitly commits or > rolls back an active transaction prior to calling the close method. If > the close method is called and there is an active transaction, the > results are implementation-defined. > " > If a commit is not being explicitly issued, then the commit behaviour should honor that of the connection, yes? > There *is* an implicit COMMIT executed if the autocommit flag is > flipped for any reason, either true->false or false->true. > > If you have autocommit=false in your configuration (which > you do), then calling setAutoCommit(false) shouldn't do anything. > >> If I put in this in the close() method of my DAO Factory >> >> if (!this.dbConn.getAutoCommit()) { this.dbConn.rollback(); } >> >> before the close() call, then update #2 is correctly not getting >> committed. > > This is probably the wrong approach: your close() method doesn't know > whether it's better to call commit() or rollback(), so it should do > neither. I realise this too, however I have to have it in otherwise if an exception is thrown, then work is being committed regardless of the fact that I have autocommit turned OFF in 3 levels, all the way back to the mysqld configuration. This behaviour does not happen with commons dbcp, only tomcat dbcp. There is a difference in default behaviour between the two pools when a transaction is not explicitly committed or rolled back when a connection is closed and returned to the pool. I use a try-with-resources/finally to open and close my database connections, thus short of a JVM crash, any exceptions thrown will always close the connections and return them to the pool. Thought: Perhaps the transaction marker is not being reset when a pooled connection is being handed out to a subsequent request for a connection, and that new servlet's work is committing the work from the first servlet that should not have been committed. Chris - To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
Re: tomcat 8.5.23 dbcp not honoring autocommit = false?
-BEGIN PGP SIGNED MESSAGE- Hash: SHA256 Chris, Sorry, I had the autocommit true/false values mixed up in my mind. When you say you have "autocommit disabled in mysql config" what do you mean? On 10/13/17 10:17 AM, Chris Cheshire wrote: > > > As a further test I just took out my explicit rollback in my > DAOFactory close() method, and swapped back to commons dbcp. Added > an update that wasn't explicitly committed, and it correctly did > not get committed when the connection was closed. Swapped back to > tomcat dbcp and repeated, it got committed without an explicit > commit statement. > > I'm really puzzled as to why *I* have to explicitly rollback on > close if autocommit is not enabled, instead of tomcat dbcp handling > that when commons dbcp appears to do it. No connection pool can read your mind. If you begin a transaction (or never start one), you must either commit or rollback. Merely calling close() does not explicitly cause either of those to be called. > If I do > > daoFactory = new MySQLDAOFactoryImpl(getDataSource()); > > // update #1 daoFactory.commit() > > // update #2 daoFactory.close(); > > then update #2 is being committed. I'm curious why you are doing "update #2" without either COMMIT or ROLLBACK. That seems like ... a mistake. - From the Connection.close() javadoc: " It is strongly recommended that an application explicitly commits or rolls back an active transaction prior to calling the close method. If the close method is called and there is an active transaction, the results are implementation-defined. " There *is* an implicit COMMIT executed if the autocommit flag is flipped for any reason, either true->false or false->true. If you have autocommit=false in your configuration (which you do), then calling setAutoCommit(false) shouldn't do anything. > If I put in this in the close() method of my DAO Factory > > if (!this.dbConn.getAutoCommit()) { this.dbConn.rollback(); } > > before the close() call, then update #2 is correctly not getting > committed. This is probably the wrong approach: your close() method doesn't know whether it's better to call commit() or rollback(), so it should do neither. - -chris -BEGIN PGP SIGNATURE- Comment: GPGTools - http://gpgtools.org Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQIzBAEBCAAdFiEEMmKgYcQvxMe7tcJcHPApP6U8pFgFAlnhKXEACgkQHPApP6U8 pFhZmw/9FN376aEpeGwzLRnpWy0jIo7EezNXeV4G5Jtj1slDeqbFMOYcm/3bdSEt sa+9FwHbe9gKMyeLWp3TJbDZ8F0RI+e2CIYV37XAchrDvpb+f80M+SjzPyuovO6a 9wRtbekKd8mbIfpGTfokjW+pNIJBbAJvZfh0UGFJP+VRX5XoE6MLzw60OnEMlmLP 7IFAdvM0t816Nuh7yJIg63I3eHYB3P7cx01ETEhWyI1oK2LQ50cODfgLoxT3iC+j f8HAyn8wubZSkC3PKJ/oY8TGaLczSt8M/ANAucZ0mw91j7m93OB+3KGwVczGRUiD lodMS9RZBsGmNxxzKcCUCmxydat2PRYJSmP/hRR0nQL7xRPiClAi4KJTWFCdn0hc SNZp8shT9Z5EVBNHJ9z2ippW7K5Xr+U58bYrN+kEmq8jN5UTUcQlDoahwnRbRWV5 CCBX+9P+fd44yWuK5IGkFcuKr68LmZYHarZlL5OTxfretKB7QX9B4o4x6J8PhhFj vnfJPlQCkKkuRyuSGTneLqM+f+CrQq7nquVxUmgUPF2btqNe1d21/g8AN8+FSdKS YgiZ/OstBdoDHVxnfxDJQcwY8IG9qg/didN7oaNAdelulcdIFx8Ob7PEdEmXZlrV o3vs2ntI7dCjfr0vfbvkzqrwXGgEMIPvukggB+DTgRxpYKJfCRM= =/fEQ -END PGP SIGNATURE- - To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
Re: tomcat 8.5.23 dbcp not honoring autocommit = false?
As a further test I just took out my explicit rollback in my DAOFactory close() method, and swapped back to commons dbcp. Added an update that wasn't explicitly committed, and it correctly did not get committed when the connection was closed. Swapped back to tomcat dbcp and repeated, it got committed without an explicit commit statement. I'm really puzzled as to why *I* have to explicitly rollback on close if autocommit is not enabled, instead of tomcat dbcp handling that when commons dbcp appears to do it. - To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
Re: tomcat 8.5.23 dbcp not honoring autocommit = false?
On Thu, Oct 12, 2017 at 11:16 PM, Christopher Schultzwrote: > -BEGIN PGP SIGNED MESSAGE- > Hash: SHA256 > > Chris, > > On 10/11/17 5:21 PM, Chris Cheshire wrote: >> Working on a migration from 7 to 8.5, and in it I am now using the >> tomcat dbcp, instead of apache commons dbcp.> I have found that >> with no other changes to the db code (except the factory param for >> the resource), it is working fine other than there is an implicit >> commit happening when I close a connection, even with autocommit >> turned off in mysql config, resource config AND in my code. > Your complaint is very close to my heart, here. <3 > > Back in 2003 or so, I posted roughly this exact question to this > mailing list with a little less ... diplomacy, shall we say? > >> try { this.dbConn = this.dataSource.getConnection(); >> this.dbConn.setAutoCommit(false); >> this.dbConn.setTransactionIsolation(Connection.TRANSACTION_READ_COMMIT > TED); >> >> > } >> catch (SQLException ex) { throw new DAOException("unable to get >> database connection", ex); } > > I'll bet you've had this problem for a really long time, but just > didn't notice it until now. > Nope, only since swapping from commons dbcp (tomcat 7.x) to tomcat dbcp in development. I started with 8.5.20 and upgraded yesterday to 8.5.23 and it still exhibits this behaviour. > The core problem is that you have autocommit=false in your > configuration and autocommit=true in your code. If an exception occurs > and you don't rollback the transaction, the connection pool will reset > all of the settings to your configured settings (including > autocommit=true). Setting autocommit=true when autocommit=false > commits the transaction, which is SUPER surprising to anyone who > hasn't read the Javadoc[1] > I *don't* have autocommit=true in code, unless this.dbConn.setAutoCommit(false); doesn't mean what I think it means. You even have it in your example! > Technically, this happens whether you encounter an exception or not, > but it's fairly rare to have code that intentionally does this: > > conn.setAutoCommit(false); > // UPDATE ...; > conn.close(); > > So, given that this is usually an "exceptional" situation, it's your > exceptions you need to carefully handle. In fact, you need to do more > than you are used to doing. > > Have a look at this post I did years later when related questions kept > coming up on the list: > http://blog.christopherschultz.net/index.php/2009/03/16/properly-handlin > g-pooled-jdbc-connections/ > I have autocommit set to false in 3 ways : 1) /etc/my.conf : autocommit=0 2) context.xml resource def : defaultAutoCommit=false 3) in code : dbConn.setAutoCommit(false) When I query autocommit on the connection it returns false, yet transactions are being committed when I issue a close() on the connection after making changes and not explicitly committing. Color me very, very confused. - To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
Re: tomcat 8.5.23 dbcp not honoring autocommit = false?
-BEGIN PGP SIGNED MESSAGE- Hash: SHA256 Chris, On 10/11/17 5:21 PM, Chris Cheshire wrote: > Working on a migration from 7 to 8.5, and in it I am now using the > tomcat dbcp, instead of apache commons dbcp.> I have found that > with no other changes to the db code (except the factory param for > the resource), it is working fine other than there is an implicit > commit happening when I close a connection, even with autocommit > turned off in mysql config, resource config AND in my code. Your complaint is very close to my heart, here. <3 Back in 2003 or so, I posted roughly this exact question to this mailing list with a little less ... diplomacy, shall we say? > try { this.dbConn = this.dataSource.getConnection(); > this.dbConn.setAutoCommit(false); > this.dbConn.setTransactionIsolation(Connection.TRANSACTION_READ_COMMIT TED); > > } > catch (SQLException ex) { throw new DAOException("unable to get > database connection", ex); } I'll bet you've had this problem for a really long time, but just didn't notice it until now. The core problem is that you have autocommit=false in your configuration and autocommit=true in your code. If an exception occurs and you don't rollback the transaction, the connection pool will reset all of the settings to your configured settings (including autocommit=true). Setting autocommit=true when autocommit=false commits the transaction, which is SUPER surprising to anyone who hasn't read the Javadoc[1] Technically, this happens whether you encounter an exception or not, but it's fairly rare to have code that intentionally does this: conn.setAutoCommit(false); // UPDATE ...; conn.close(); So, given that this is usually an "exceptional" situation, it's your exceptions you need to carefully handle. In fact, you need to do more than you are used to doing. Have a look at this post I did years later when related questions kept coming up on the list: http://blog.christopherschultz.net/index.php/2009/03/16/properly-handlin g-pooled-jdbc-connections/ Hope that helps, - -chris -BEGIN PGP SIGNATURE- Comment: GPGTools - http://gpgtools.org Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQIzBAEBCAAdFiEEMmKgYcQvxMe7tcJcHPApP6U8pFgFAlngMBoACgkQHPApP6U8 pFhdjBAAl2u3lxKhrjKdmtjUgtYp0/gOfTPq7jXjdgZBrkSNh9q6I8dJ6gQOsECV TkCQ2LH8tAUpuUYWCt7QJRLQPVAuwrzplue1InlTFCS8I1b/WK7vQk93teB4I0Ia HKaC4RGGtgKgS//PsCRxDdFgo0Hzr+hA+nte1qFytmla8ZRZjimbz5EnWJpNwYoU XjEjhaF6wdVOHP8zKU9/CIc3XQKC1kfQb9Rodb9SZTpjFDTw12NsBjEXG5evY8XJ A2PPxHPiRdyyHq2R1MDWGFWdSdCsY4pFq4nvNExEuIuHg1/C+GlGUENLH3MiJNPY minxeaKykVfmUd2zJvWjxmhrdw8nHT3ThtAHA0BgU7thBCenANFbSBxx7+39Jxg/ eDEW4dEqOP3c/ZvifpMrGxjJ0zXBXDu7Jik4KFEzMWI8oaAl3hSSDwEe7FEJE41Y lDv+LjcBgDwSHLfTbau+0xJx79wAKTAFY7v7uGujUgDZqWsRG1znyZx+OuZnbWxQ JSbQSJ3pOMerybeJMuHx1a4y+HwA4t0GtLigeRMeyFvTqqtfCVasr3ONMh22XYIU OORbLADRwjbqYnswvxRC06FfKvU8AhNwuybt/XzHrTfURuIZWx7GRycMlaEMaUdS OdWlW6Zf3+fWfUxg05zIX3q2Ug4h2O1zW+ccPOrs5bswE9EEAZM= =eyik -END PGP SIGNATURE- - To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org