END_RESPONSE message is not sent when the request duration exceeds the write-timeout on ajp-listener with CPING/CPONG enabled

Issue

If the request duration exceeds write-timeout in ajp-listener with ping enabled in ProxyPass directive on httpd-side, we can see the following error in Apache's error_log.

ProxyPass "/app/" "ajp://127.0.0.1:8009/app/" ping=10 ttl=55 timeout=120

HTTPD_HOME/logs/error_log

[Thu Dec 05 17:31:33.334793 2024] [proxy_ajp:error] [pid 60300:tid 60320] (70014)End of file found: AH01030: ajp_ilink_receive() can't receive header
[Thu Dec 05 17:31:33.334836 2024] [proxy_ajp:error] [pid 60300:tid 60320] [client 127.0.0.1:45284] AH00992: ajp_read_header: ajp_ilink_receive failed
[Thu Dec 05 17:31:33.334845 2024] [proxy_ajp:error] [pid 60300:tid 60320] (120006)APR does not understand this error code: [client 127.0.0.1:45284] AH00893: dialog to 127.0.0.1:8009 (127.0.0.1:8009) failed

If we check the packet capture, we can confirm that the END_RESPONSE message was not sent.

1    2024-12-05 17:29:53.081136    127.0.0.1    127.0.0.1    TCP    74    42054 → 8009 [SYN] Seq=0 Win=65495 Len=0 MSS=65495 SACK_PERM TSval=3760530610 TSecr=0 WS=128
2    2024-12-05 17:29:53.081140    127.0.0.1    127.0.0.1    TCP    74    8009 → 42054 [SYN, ACK] Seq=0 Ack=1 Win=65483 Len=0 MSS=65495 SACK_PERM TSval=3760530610 TSecr=3760530610 WS=128
3    2024-12-05 17:29:53.081144    127.0.0.1    127.0.0.1    TCP    66    42054 → 8009 [ACK] Seq=1 Ack=1 Win=65536 Len=0 TSval=3760530610 TSecr=3760530610
4    2024-12-05 17:29:53.081188    127.0.0.1    127.0.0.1    AJP13    71    2:REQ:CPING
5    2024-12-05 17:29:53.081189    127.0.0.1    127.0.0.1    TCP    66    8009 → 42054 [ACK] Seq=1 Ack=6 Win=65536 Len=0 TSval=3760530610 TSecr=3760530610
6    2024-12-05 17:29:53.090263    127.0.0.1    127.0.0.1    AJP13    71    2:RSP:CPONG
7    2024-12-05 17:29:53.090271    127.0.0.1    127.0.0.1    TCP    66    42054 → 8009 [ACK] Seq=6 Ack=6 Win=65536 Len=0 TSval=3760530619 TSecr=3760530619
8    2024-12-05 17:29:53.090330    127.0.0.1    127.0.0.1    AJP13    243    2:REQ:GET /app/slow.jsp HTTP/1.1
9    2024-12-05 17:29:53.132099    127.0.0.1    127.0.0.1    TCP    66    8009 → 42054 [ACK] Seq=6 Ack=183 Win=65536 Len=0 TSval=3760530661 TSecr=3760530619
10   2024-12-05 17:31:33.333474    127.0.0.1    127.0.0.1    AJP13    350    2:RSP:SEND BODY CHUNK
11   2024-12-05 17:31:33.334781    127.0.0.1    127.0.0.1    TCP    66    8009 → 42054 [FIN, ACK] Seq=290 Ack=183 Win=65536 Len=0 TSval=3760630863 TSecr=3760530619   <<<=== FIN from server-side without END RESPONSE message
12   2024-12-05 17:31:33.334861    127.0.0.1    127.0.0.1    TCP    66    42054 → 8009 [FIN, ACK] Seq=183 Ack=291 Win=65536 Len=0 TSval=3760630863 TSecr=3760630862
13   2024-12-05 17:31:33.334875    127.0.0.1    127.0.0.1    TCP    66    8009 → 42054 [ACK] Seq=291 Ack=184 Win=65536 Len=0 TSval=3760630863 TSecr=3760630863