在多线程环境中重用JAX RS Client（具有resteasy） [英] Reusing JAX RS Client in multi-threaded environment (with resteasy)

问题描述

根据文档，

客户端是管理客户端
通信基础设施的重量级对象。初始化以及处理
客户端实例可能是一项相当昂贵的操作。因此建议
建议在
应用程序中仅构造少量客户端实例。

"Clients are heavy-weight objects that manage the client-side communication infrastructure. Initialization as well as disposal of a Client instance may be a rather expensive operation. It is therefore advised to construct only a small number of Client instances in the application. "

好的，我正在尝试在一个静态变量中缓存Client本身和WebTarget实例，在多线程环境中调用someMethod（）： / p>

Ok, I'm trying to cache Client itself and WebTarget instances in a static variable, the someMethod() is invoked in multi-threaded environment:

private static Client client = ClientBuilder.newClient();
private static WebTarget webTarget = client.target("someBaseUrl");
...
public static String someMethod(String arg1, String arg2)
{
    WebTarget target = entrTarget.queryParam("arg1", arg1).queryParam("arg2", arg2);
    Response response = target.request().get();
    final String result = response.readEntity(String.class);
    response.close();
    return result;
}

但有时（并非总是）我得到一个例外：

But sometimes (not always) I'm get an exception:

无效使用BasicClientConnManager：仍然分配了连接。
确保在分配另一个连接之前释放连接。

Invalid use of BasicClientConnManager: connection still allocated. Make sure to release the connection before allocating another one.

如何正确地重用/缓存Client / WebTarget？是否可以使用JAX RS Client API？或者我必须使用一些特定于框架的功能（resteasy / jersey）你能提供一些示例或文档吗？

How can Client/WebTarget be reused/cached correctly? Is it possible with JAX RS Client API? Or I have to use some framework-specific features (resteasy/jersey) Could you provide some example or documentation?

推荐答案

您的实施不是线程安全的。当两个线程同时访问 someMethod 时，他们共享相同的客户端，并且会尝试发出第二个请求而第一个没有完成。

Your implementation is not thread-safe. When two threads access someMethod at the same time they are sharing the same Client and one will try to make a second request while the first one is not finished.

您有两种选择：

• 同步对<$ c的访问权限$ c>客户端和 WebTarget 手动。


• 让容器通过注释封闭类型来管理并发 @ javax.ejb.Singleton 保证线程安全。 （参见 EJB规范）

• Synchronize the access to the Client and WebTarget manually.
• Let the container manage concurrency by annotating the enclosing type with @javax.ejb.Singleton which guarantees thread safety. (see chapter 4.8.5 of the EJB specification)

如果 someMethod 在容器管理环境中，我会使用第二种方法。

If someMethod in a container managed environment I would use the second approach.

这篇关于在多线程环境中重用JAX RS Client（具有resteasy）的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！