Weld SiteCommunity Documentation

Chapter 19. Configuration

19.1. Weld configuration
19.1.1. Relaxed construction
19.1.2. Concurrent deployment configuration
19.1.3. Thread pool configuration
19.1.4. Non-portable mode during application initialization
19.1.5. Bounding the cache size for resolved injection points
19.1.6. Debugging generated bytecode
19.1.7. Injectable reference lookup optimization
19.1.8. Bean identifier index optimization
19.1.9. Development Mode
19.2. Excluding classes from scanning and deployment
19.3. Mapping CDI contexts to HTTP requests

Weld can be configured per application through the set of properties. All the supported configuration properties are described in the following subsections.

Each configuration property can be specified (by priority in descending order):

  1. In a properties file named weld.properties
  2. As a system property
  3. By a bootstrap configuration provided by an integrator

If a configuration key is set in multiple sources (e.g. as a system property and in a properties file), the value from the source with higher priority is taken, other values are ignored. Unsupported configuration keys are ignored. If an invalid configuration property value is set, the container automatically detects the problem and treats it as a deployment problem.

For certain types of tasks Weld uses its own thread pool. The thread pool is represented by the ExecutorServices service.

First of all, let’s see what types of thread pools are available:

Thread pool typeDescription


Uses a fixed number of threads. The number of threads remains the same throughout the application.


Uses a fixed number of threads. A thread will be stopped after a configured period of inactivity.


A single-threaded thread pool


No executor is used by Weld


The default ForkJoinPool.commonPool() is used by Weld. See link for more details

Now let’s see how to configure Weld to use a particular thread pool type:


It’s possible to alter the thread pool configuration using the deprecated org.jboss.weld.executor.properties file located on the classpath. The keys are threadPoolType, threadPoolSize, threadPoolKeepAliveTime and threadPoolDebug.

CDI 1.1 allows you to exclude classes in your archive from being scanned, having container lifecycle events fired, and being deployed as beans. See also 12.4. Bean discovery.


Weld still supports the original non-portable way of excluding classes from discovery. The formal specification can be found in the xsd, located at http://jboss.org/schema/weld/beans_1_1.xsd. Unlike Weld, the CDI specification does not support regular expression patterns and ! character to invert the activation condition.

All the configuration is done in the beans.xml file. For more information see Section 15.6, “Packaging and deployment”.

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://xmlns.jcp.org/xml/ns/javaee">


        <!-- Don't deploy the classes for the swing app! -->
        <exclude name="com.acme.swing.**" />

        <!-- Don't include GWT support if GWT is not installed -->
        <exclude name="com.acme.gwt.**">
            <if-class-not-available name="com.google.GWT"/>

            Exclude types from com.acme.verbose package if the system property verbosity is set to low
              java ... -Dverbosity=low
        <exclude name="com.acme.verbose.*">
            <if-system-property name="verbosity" value="low"/>

             Don't include JSF support if Wicket classes are present, and the viewlayer system
             property is set
        <exclude name="com.acme.jsf.**">
            <if-class-available name="org.apache.wicket.Wicket"/>
            <if-system-property name="viewlayer"/>


In this example we show the most common use cases for exercising fine control over which classes Weld scans. The first filter excludes all types whose package name starts with com.acme.swing, and in most cases this will be sufficient for your needs.

However, sometimes it’s useful to be able to activate the filter depending on the environment used. In this case, Weld allows you to activate (or deactivate) a filter based on either system properties or whether a class is available. The second filter shows the use case of disabling scanning of certain classes depending on the capabilities of the environment you deploy to - in this case we are excluding GWT support (all types whose package name starts with com.acme.gwt) if GWT is not installed.


If you specify just a system property name, Weld will activate the filter if that system property has been set (with any value). If you also specify the system property value, then Weld will only activate the filter if the system property’s value matches exactly.

The third filter shows how to exclude all types from a specific package (note the name attribute has suffix ".*").

The fourth filter shows more a advanced configurations, where we use multiple activation conditions to decide whether to activate the filter.

You can combine as many activation conditions as you like (all must be true for the filter to be activated). If you want to a filter that is active if any of the activation conditions are true, then you need multiple identical filters, each with different activation conditions.

By default, CDI contexts are activated at the beginning of an HTTP request processing and deactivated once the processing finishes. This may represent an unnecessary overhead in certain situations, for example static resource serving.

Weld allows CDI context support to be mapped to a certain subset of requests only. A regular expression may be used for filtering HTTP requests that should have CDI contexts active during their processing.

<web-app version="3.1" xmlns="http://xmlns.jcp.org/xml/ns/javaee/"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd">