SSL Proxy connect failed and mod_cluster returns "Bad Gateway" HTTP ErrorCode 502

Issue

• We have Apache/mod_cluster loadbalancing traffic to JBoss over SSL. After a longer pause with no requests (e.g. in the morning), many requests fail with 502 "Bad Gateway" errors. Apache debug logging shows it occurs it is triggered from a failure in the SSL handshake:

  [debug] ssl_engine_kernel.c(1902): OpenSSL: Read: SSLv2/v3 read server hello A
  [debug] ssl_engine_kernel.c(1926): OpenSSL: Exit: error in SSLv2/v3 read server hello A
  [info] [client 127.0.0.1] SSL Proxy connect failed
  [info] SSL Library Error: 336032754 error:140773F2:SSL routines:SSL23_GET_SERVER_HELLO:sslv3 alert unexpected message
  [info] [client 127.0.0.1] Connection closed to child 0 with abortive shutdown (server localhost:443)
  [error] (502)Unknown error 502: proxy: pass request body failed to localhost:8443 (127.0.0.1)
  

• On jboss.org, I found the following thread

• After multiple requests, the error is gone and everything works fine. Just after a longer pause the error comes back. Also, restarting Apache appears to clear up the 502s until another period of idleness.