Inspect Java HTTP connection pool

Question

HttpUrlConnection uses persistent connections by default (http://download.oracle.com/javase/6/docs/technotes/guides/net/http-keepalive.html). Is there any way to inspect Java HTTP connection pool? Eg check how many open connections in the pool?

Answer 1

Unfortunately no. In Oracle's VM, you can in theory inspect the static cache in sun.net.www.http.HttpClient.kac using reflection. This is a Map, which values are Stacks of cached HttpClient instances. The cache however also contains already closed or timed out connections and it does not seem to be a reasonable easy way to filter these out, without actually performing a real HTTP request, in which case abandoned connections will automatically reconnect.