DefaultHttpClient 的单例实例超时

Question

I'm using a singleton instance of DefaultHttpClient in conjunction with PoolingClientConnectionManager to perform a cconsiderable number (multiple per second) of HTTP operations in a multithreaded fashion. My code is basically:

final HttpParams httpClientParams = new BasicHttpParams();
httpClientParams.setParameter("http.protocol.version", HttpVersion.HTTP_1_1);
HttpConnectionParams.setConnectionTimeout(httpClientParams, 700);
HttpConnectionParams.setSoTimeout(httpClientParams, 700);
DefaultHttpClient client = new DefaultHttpClient(poolingClientConnectionManager, httpClientParams);

I will then access the client object from multiple threads in parallel.

My problem is, that the timeouts do not get respected and I have HTTP requests that take much longer than the 700ms specified.

• Is it safe to set the timeout on the client as I do above?
• Is it safe to use a singleton instance of DefaultHttpClient for many parallel requests?

Answer 1

• Is it safe to set the timeout on the client as I do above?

Yes, it is safe. However, HttpClient level parameters represent the default settings inherited by all requests. One should not meddle with those settings at runtime. It is generally better to use request level parameters to configure individual requests.

• Is it safe to use a singleton instance of DefaultHttpClient for many parallel requests?

Not only safe but also strongly advisable. By sharing the same HttpClient instance individual requests can be executed more efficiently by re-using a shared pool of persistent connections.

Please also make sure your expectations with regards to timeout behavior are correct. Timeout values represent the maximum period of inactivity between two consecutive i/o operations, not the maximum total request execution time.