HttpClient connection pool over two internets - apache-httpclient-4.x

Question

I am experiencing some problems in my client's environment.
It has 2 internet providers, the second is a backup when the first one goes down, both managed by the Pfsence instance.
I am using HttpClient to make requests to another server on a VPN managed by this pfsence instance as well.
When the first internet goes down (the second takes over), but HttpClient has an internal connection pool
(PoolingHttpClientConnectionManager) and there is my problem ...
This pool is holding a socket instance that does not time out (I don’t know why) and the next requests that must use the second internet stop responding because the pool has dilivery that socket connected by the first internet that is down now, and it doesn't result in a read timeout or something like that ...
How can I solve this? How can I test this pool and discard these connectors in the right way?

Answer 1

I created a health-check thread and each time the server refuses a connection I evict the pool:
Thread healthCheck = new Thread(() -> {
while (true) {
try (Socket s = new Socket()) {
s.connect(new InetSocketAddress("ip-server-address", 80), 3000);
} catch (IOException e) {
myPoolingHttpClientConnectionManager.closeExpiredConnections();
myPoolingHttpClientConnectionManager.closeIdleConnections(0, TimeUnit.MILLISECONDS);
}
try {
Thread.sleep(5000);
} catch (InterruptedException e) {
return;
}
}
});
healthCheck.setDaemon(true);
healthCheck.start();
This solution was based on this article:
https://www.baeldung.com/httpclient-connection-management#eviction