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From Robb Wagoner <r...@pandastrike.com>
Subject Re: MySQL Deadlocks in OfBiz 12.04
Date Fri, 17 Feb 2017 12:25:17 GMT
Thanks Scott! Much appreciated. The pattern makes sense. Have a great
weekend.


On Wed, Feb 15, 2017 at 8:05 PM Scott Gray <scott.gray@hotwaxsystems.com>
wrote:

For example, a current project has some heavily used FinAccount rows and
the OFBiz implementation has a tendency to modify the child rows
(FinAccountAuth/FinAccountTrans) before modifying the parent FinAccount
row.  This very easily results in a deadlock as soon as one of the
competing transactions attempts to perform an update on the FinAccount
record.  This happens because the child row modifications result in a
shared lock on the parent row due to the foreign key constraint, but once
multiple transactions both have that shared lock, neither can update the
FinAccount without causing a deadlock exception.

So my quick fix solution is to acquire a lock on the FinAccount record
*before* any child rows are modified:
delegator.storeByCondition("FinAccount", UtilMisc.toMap("lastUpdatedStamp",
UtilDateTime.nowTimestamp()), EntityCondition.makeCondition("finAccountId",
finAccountId));

Assuming all code paths relating to modifying FinAccount data are following
this strategy then each transaction will have to queue on this update
statement until their turn comes up.  Voila, deadlocks are gone.

Regards
Scott


On 16 February 2017 at 09:29, Robb Wagoner <robb@pandastrike.com> wrote:

> Thanks Scott. Since I am new to OfBiz can you provide a code example? I.e.
> by what means are you issuing an arbitrary no-op update statement on a
> parent row?
>
> On Wed, Feb 15, 2017 at 1:02 PM Scott Gray <scott.gray@hotwaxsystems.com>
> wrote:
>
> Hi Robb,
>
> I've encountered similar deadlocks in the past and have simply issued an
> update statement on the main row before attempting to work with any child
> rows. That has the same effect as the FOR UPDATE statement but without
> needing to enhance the framework.
>
> Regards
> Scott
>
> On 16/02/2017 08:03, "Robb Wagoner" <robb@pandastrike.com> wrote:
>
> > We are running OfBiz 12.04 and are using MySQL 5.6 as the RDBMS. We are
> > experiencing database deadlocks and would like to be able to add
> > MySQL-specific statements to deal with the deadlocks. For example:
> `SELECT
> > ... FOR UPDATE` on PRIMARY KEYs and/or FOREIGN KEYs in the transactions.
> >
> > Being new to OfBiz, I've been reviewing the ofbiz-user and ofbiz-dev
> > archives, OfBiz Wiki, Packt's *Apache OfBiz Cookbook*, and other
> resources
> > to learn how we can achieve this.
> > I see mentions of deadlocks in the archives and in JIRA issues (
> > https://issues.apache.org/jira/browse/OFBIZ-5065). Nothing conclusive or
> > directly actionable on managing/dealing with deadlocks is mentioned.
> >
> > What is the OfBiz-way of dealing with RDBMS deadlocks?
> >
> >
> > *Deadlocking statements:*
> > UPDATE SHIPMENT
> > UPDATE INVENTORY_ITEM
> > UPDATE GL_ACCOUNT_ORGANIZATION
> > INSERT INTO ACCTG_TRANS_ENTRY
> >
> >
> > *entityengine.xml datasource element:*
> > <datasource name="localmysql"
> >             helper-class="org.ofbiz.entity.datasource.GenericHelperDAO"
> >             field-type-name="mysql"
> >             check-on-start="true"
> >             add-missing-on-start="true"
> >             check-pks-on-start="false"
> >             check-indices-on-start="false"
> >             use-foreign-keys="true"
> >             join-style="ansi-no-parenthesis"
> >             alias-view-columns="false"
> >             drop-fk-use-foreign-key-keyword="true"
> >             table-type="InnoDB"
> >             character-set="utf8"
> >             collate="utf8_general_ci">
> >         <read-data reader-name="tenant"/>
> >         <read-data reader-name="seed"/>
> >         <read-data reader-name="seed-initial"/>
> >         <read-data reader-name="demo"/>
> >         <read-data reader-name="ext"/>
> >         <inline-jdbc
> >                 jdbc-driver="com.mysql.jdbc.Driver"
> >                 jdbc-uri="jdbc:mysql://
> > ofbiz-db.example.com/ofbiz?autoReconnect=true"
> >                 jdbc-username="ofbiz"
> >                 jdbc-password="XXXXpasswordXXXX"
> >                 isolation-level="ReadCommitted"
> >                 pool-minsize="2"
> >                 pool-maxsize="250"
> >                 time-between-eviction-runs-millis="600000"/><!-- Please
> > note that at least one person has experienced a problem with this value
> > with MySQL
> >                 and had to set it to -1 in order to avoid this issue.
> >                 For more look at http://markmail.org/thread/
> > 5sivpykv7xkl66px
> > and http://commons.apache.org/dbcp/configuration.html-->
> >         <!-- <jndi-jdbc jndi-server-name="localjndi"
> > jndi-name="java:/MySqlDataSource" isolation-level="Serializable"/> -->
> >     </datasource>
> >
>

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