HttpClient 4.3.5 ConnectionRequestTimeOut vs ConnectTimeout for HttpConnectionParams.setConnectionTimeout in 4.0.1

Question

I am trying to upgrade our HttpClient Dependency from 4.0.1 to 4.3.5. And was confused on setting the connection timeout in the new lib. For the following code:

HttpClient httpClient = new DefaultHttpClient();
HttpConnectionParams.setConnectionTimeout(httpClient.getParams(), 300);

It will be replaced with the code below:

RequestConfig config = RequestConfig.custom().setConnectTimeout(300).build();
HttpClient httpClient = HttpClientBuilder.create().setDefaultRequestConfig(config).build();

However, I am not sure if I should use setConnectTimeout or setConnectionRequestTimeout since I am not familiar with HttpClient. It seems to me I should use setConnectionTimeout based on the java doc in the source code. Can somebody please confirm? Thanks in advance.

https://svn.apache.org/repos/asf/httpcomponents/httpclient/tags/4.3.3/httpclient/src/main/java/org/apache/http/client/config/RequestConfig.java

/**
 * Returns the timeout in milliseconds used when requesting a connection
 * from the connection manager. A timeout value of zero is interpreted
 * as an infinite timeout.
 * <p/>
 * A timeout value of zero is interpreted as an infinite timeout.
 * A negative value is interpreted as undefined (system default).
 * <p/>
 * Default: <code>-1</code>
 */
public int getConnectionRequestTimeout() {
    return connectionRequestTimeout;
}

/**
 * Determines the timeout in milliseconds until a connection is established.
 * A timeout value of zero is interpreted as an infinite timeout.
 * <p/>
 * A timeout value of zero is interpreted as an infinite timeout.
 * A negative value is interpreted as undefined (system default).
 * <p/>
 * Default: <code>-1</code>
 */
public int getConnectTimeout() {
    return connectTimeout;
}

Answer 1

In version 4.3 of Apache Http Client the configuration was refactored (again). the new way as the following code:

RequestConfig requestConfig =RequestConfig.custom()
.setConnectTimeout(connectTimeout)
.setConnectionRequestTimeout(connectionRequestTimeout)
.setSocketTimeout(socketTimeout).build();

connectTimeout is the timeout until a connection with the server is established. connectionRequestTimeout is used when requesting a connection from the connection manager.

Answer 2

Difference between the three timeouts in Apache HttpClient :

connectTimeout max time to establish a connection with remote host/server.

connectionRequestTimeout time to wait for getting a connection from the connection manager/pool. (HttpClient maintains a connection pool to manage the connections. Similar to database connection pool)

socketTimeout max time gap between two consecutive data packets while transferring data from server to client.