How to set TCP keep Alive in java from httpclient

Syam S :

My java application which resides in AWS private subnet connects to an http server via AWS Nat gateway. I am calling a POST request via httpclient to the HTTP server. That request will take more than 10 minutes to complete. I have configured a socket time out and connection timeout of 1 hour as this this a background task . But the intermediate AWS NAT gateway will send back a RST packet after 300 secs [5 mins] and cause the connection to get resetted , there is no way i can increase the NAT gateway timeout. So i need to handle the problem from my application side.

My strategy is to use a tcp keep alive time which will send a packet say every 240 secs to keep the connection active. I have configured this as below

CloseableHttpClient httpClient = HttpClients.createDefault()
HttpParams params = httpClient.getParams();
HttpConnectionParams.setConnectionTimeout(params, 3600000); //connection Timeout
HttpConnectionParams.setSoTimeout(params, 3600000); // Socket Time out
HttpConnectionParams.setSoKeepalive(params, true); //Enable Socket level keep alive time

and then call the post request via execute method

HttpPost post = new HttpPost("http://url");
HttpResponse response = httpClient.execute(post);

Since i am using a linux system i have configured the server with following Sysctl values

sysctl -w net.ipv4.tcp_keepalive_time=240 
sysctl -w net.ipv4.tcp_keepalive_intvl=240
sysctl -w net.ipv4.tcp_keepalive_probes=10

But while executing the program the keep alive is not enabled and connection fails as previous.

I have checked this with netstat -o option and as shown below keep alive is off

tcp        0      0 192.168.1.141:43770     public_ip:80          ESTABLISHED 18134/java           off (0.00/0/0)

Is there any way i can set TCP keep alive from java code using httpclient . Also i can see HttpConnectionParams are deprecated. But I couldnt find any new class which can set keep alive

Thanks

Syam S :

I have found a solution to the problem . Curious case is there is no way i can use some builder class in httpclient to pass socket keep alive . One method as i specified in the question is using HttpConnectionParams as below but this is not working and this class is now deprecated.

HttpParams params = httpClient.getParams();
HttpConnectionParams.setSoKeepalive(params, true);

So while checking apache http docs I can see that now connection parameters are passed to httpclient via RequestConfig class . Builders of this class provide solution to set connection_time_out and socket_time_out. But checking the socurce code of this I couldnt see an option to enable SocketKeepAlive which is what we want. So the only solution is directly creating a Socket using SocketBuilder class and pass that to the HttpClientBuilder.

Following is the working code

SocketConfig socketConfig = SocketConfig.custom().setSoKeepAlive(true).setSoTimeout(3600000).build(); //We need to set socket keep alive
        RequestConfig requestConfig = RequestConfig.custom().setConnectTimeout(3600000).build();
        CloseableHttpClient httpClient = HttpClientBuilder.create().setDefaultRequestConfig(requestConfig).
                                           setDefaultSocketConfig(socketConfig).build();
HttpPost post = new HttpPost(url.toString());
HttpResponse response = httpClient.execute(post);

While executing above i can see that keep alive is properly set in the socket based on the sysctl values i set in linux kernel

tcp        0      0 localip:48314     public_ip:443     ESTABLISHED 14863/java          keepalive (234.11/0/0)

If some one has a better solution to enable Socket Keep alive from Requestconfig class or any other high level builder class i am open to suggestions.