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| 1 | += Logging Guide |
| 2 | +:toc: |
| 3 | + |
| 4 | +Since version 4.0, Hibernate has used the JBoss Logging library for its logging needs. Like SLF4J and |
| 5 | +Jakarta's commons-logging, JBoss Logging is a "logging bridge" providing integration with numerous logging |
| 6 | +frameworks. JBoss Logging was chosen because of its i18n support and its support for "message ids". This is largely |
| 7 | +the seminal documentation of JBoss Logging since JBoss Logging currently provides no documentation of its own. |
| 8 | + |
| 9 | + |
| 10 | +== Supported Back-ends |
| 11 | + |
| 12 | +JBoss Logging understands the following back-ends as first-class citizens: |
| 13 | + |
| 14 | +. JBoss LogManager (mainly used only inside the WildFly app server) |
| 15 | +. Log4j 2 |
| 16 | +. Log4j 1 |
| 17 | +. Slf4j |
| 18 | +. JDK logging |
| 19 | + |
| 20 | +Note the order above, it is important. By default JBoss Logging will search the ClassLoader for the availability of |
| 21 | +classes that indicate one of the above "providers" being available. It does this in the order defined above. So, |
| 22 | +for example, if you have both JBoss LogManager and Slf4j available your classpath then JBoss LogManager will be used |
| 23 | +as it has the "higher precedence". |
| 24 | + |
| 25 | +This can sometimes lead to an unwanted logging set up to be used. In such cases, JBoss Logging provides for you to |
| 26 | +tell it specifically which provider to use. |
| 27 | + |
| 28 | + |
| 29 | +=== Provider setting |
| 30 | + |
| 31 | +JBoss Logging will first look for a setting with the key `org.jboss.logging.provider`, which can be set to one of the |
| 32 | +following values: |
| 33 | + |
| 34 | +. jboss |
| 35 | +. jdk |
| 36 | +. log4j2 |
| 37 | +. log4j |
| 38 | +. slf4j |
| 39 | + |
| 40 | + |
| 41 | +=== JDK Service |
| 42 | + |
| 43 | +Next, JBoss Logging will look for a JDK service (see javadocs for +java.util.ServiceLoader+ for details) for its |
| 44 | +"provider" contract (+org.jboss.logging.Provider+). If multiple are available, it will use the first one returned by |
| 45 | +the ClassLoader. |
| 46 | + |
| 47 | + |
| 48 | +== Usage |
| 49 | + |
| 50 | +Most of the time, the discovery process JustWorks. The discovery process relies on the jars available on the classpath. |
| 51 | +The jboss-logging jar is a required dependency of Hibernate and therefore will always need to be on the classpath. |
| 52 | + |
| 53 | +* To use JBoss Logging with Log4j, the log4j jar would also need to be available on the classpath. |
| 54 | +* To use JBoss Logging with Log4j2, the log4j2 jar would also need to be available on the classpath. |
| 55 | +* To use JBoss Logging with Slf4j, the slf4j-api jar would also need to be available on the classpath *plus* any needed |
| 56 | +slf4j backend. |
| 57 | + |
| 58 | +JDK Logging would be used if none of the other framework jars are available. |
| 59 | + |
| 60 | + |
| 61 | +== Log Categories of Interest |
| 62 | + |
| 63 | +It is recommended that you familiarize yourself with the log messages sent from Hibernate. A lot of work has been put |
| 64 | +into making the Hibernate loggiong as detailed as possible, without making it unreadable. It is an essential |
| 65 | +troubleshooting device. Some log categories of particular interest include: |
| 66 | + |
| 67 | +.Hibernate Log Categories of Interest |
| 68 | +|=== |
| 69 | +|Category|Description |
| 70 | + |
| 71 | +|org.hibernate.SQL |
| 72 | +|Log all SQL statements as they are executed with through JDBC |
| 73 | + |
| 74 | +|org.hibernate.type.descriptor.sql |
| 75 | +|Log all values as they are bound to JDBC parameters and extracted from JDBC results |
| 76 | + |
| 77 | +|org.hibernate.tool.hbm2ddl |
| 78 | +|Log all SQL DDL statements as they are executed during execution of any of the schema migration tools |
| 79 | + |
| 80 | +|org.hibernate.pretty |
| 81 | +|Log the state of all entities (max 20 entities) associated with the session at flush time |
| 82 | + |
| 83 | +|org.hibernate.cache |
| 84 | +|Log all second-level cache activity |
| 85 | + |
| 86 | +|org.hibernate.hql.internal.ast.AST |
| 87 | +|Log HQL and SQL ASTs during query parsing |
| 88 | + |
| 89 | +|org.hibernate |
| 90 | +|Log everything. This is a lot of information but it is useful for troubleshooting |
| 91 | +|=== |
| 92 | + |
| 93 | + |
| 94 | +== Message Id Index |
| 95 | + |
| 96 | +Coming soon. |
| 97 | + |
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