项目启动报错availableProcessors is already set to [8] rejecting [8]

背景

项目基于SpringBoot并且集成ElasticSearch，今天在编写测试类准备进行单元测试时，报了如下这个错误。

Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'client' defined in class path resource [com/lingyejun/project/ds/EsRepositoryConfig.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.elasticsearch.client.Client]: Factory method 'client' threw exception; nested exception is java.lang.IllegalStateException: availableProcessors is already set to [8], rejecting [8]
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:590)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1256)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1105)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:543)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:503)
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:317)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:315)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199)
    at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:251)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1138)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1065)
    at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:818)
    at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:724)
    ... 94 more
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.elasticsearch.client.Client]: Factory method 'client' threw exception; nested exception is java.lang.IllegalStateException: availableProcessors is already set to [8], rejecting [8]
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:185)
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:582)
    ... 107 more
Caused by: java.lang.IllegalStateException: availableProcessors is already set to [8], rejecting [8]

检查了原有代码是如下设置的

public static void main(String[] args) {

System.setProperty("es.set.netty.runtime.available.processors","false");

SpringApplication.run(TestApplication.class, args);
}

解决

查阅资料后发现有两种解决方式

1.　将代码段：System.setProperty("es.set.netty.runtime.available.processors","false")；挪到静态代码块中。

如下：

static{
    System.setProperty("es.set.netty.runtime.available.processors", "false");
}
 
public static void main(String[] args) {

    SpringApplication.run(TestApplication.class, args);
}

2.在jvm启动参数加上

-Des.set.netty.runtime.available.processors=false

原因

此问题见：Issue with NettyRuntime$AvailableProcessorsHolder: number of available processors · Issue #6956 · netty/netty · GitHub

原因是程序的其余地方使用了Netty，如大部分项目也会同时使用Redis。这会影响在实例化传输客户端以前初始化处理器的数量。 因为在其余地方使用Netty，所以已经进行了初始化而且Netty会对此进行防范，所以首次实例化会因看到的非法状态异常而失败。

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