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  1. Log4j 2
  2. LOG4J2-393

Low initialization performance when using Log4J with jar packages




      We discovered a huge performance difference when initializing Log4J with deployed jar packages compared to using it directly with normal class files.

      As it seems,
      is way slower than its counterpart
      and since this method gets called a few hundred times at initialization in this project, initialization of Log4J took more than 2 minutes with jar packages, compared to a few seconds with class files.

      The performance issue was already mentioned in LOG4J2-184, only without the jar problem.
      The solution to LOG4J2-175 might cause this, but we are unsure why the methods exactly get called this often.

      I just can tell that
      org.apache.logging.log4j.core.config.plugins.PluginManager#collectPlugins() gets called VERY often via
      org.apache.logging.log4j.core.config.BaseConfiguration#getPluginManager, which gets called by

      And collectPlugins() is remapped to collectPlugins(boolean preLoad, final String pkgs) with collectPlugins(true, null);. I'm unsure what this preLoad is for, since it gets overridden with false and apparently no kind of caching is used. In this method, resolver.findInPackage(test, pkg); takes a whole lot of time searching within the jars, as described in the beginning.

      The only way to work around this was for us to extract the custom appender in a sperate ant build target, and with this in a seperate jar, to minimize the size of the jar, reducing the search time.

      Can you cache things and maybe reduce the calls to collectPlugins()? I don't see the probability of changing plugins during initialization as described in LOG4J2-175 or the comment in org.apache.logging.log4j.core.config.BaseConfiguration#getPluginManager.
      Introducing a variable for the plugin manager within the for loop in org.apache.logging.log4j.core.config.XMLConfiguration#constructHierarchy might be a good idea!




            • Assignee:
              philipp.hedwig Philipp Hedwig
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