@sherman: FWIW, I'm seeing a similar pattern of a burst of NOOP every 2s for a while on connect, before it gets staggered a bit more towards ~10s.
It's been holding steady at ~10s for a few minutes now, and I haven't touched calibre at all during the experiment
.
(Calibre 5.7.2 on a Linux host).
Code:
Dec 17 19:39:03 KoboUNCaGED[18271]: 2020/12/17 19:39:03 [DEBUG] setTCPDeadline: setting TCP deadline to 120000 milliseconds
Dec 17 19:39:03 KoboUNCaGED[18271]: 2020/12/17 19:39:03 [DEBUG] Read TCP packet: [7, {"count": 2, "collections": {}, "wil
Dec 17 19:39:03 KoboUNCaGED[18271]: 2020/12/17 19:39:03 [DEBUG] Calibre Opcode received: 7
Dec 17 19:39:03 KoboUNCaGED[18271]: 2020/12/17 19:39:03 [DEBUG] Processing SEND_BOOKLISTS packet: {"count": 2, "collections": {}, "willStr
Dec 17 19:39:03 KoboUNCaGED[18271]: 2020/12/17 19:39:03 [DEBUG] Read TCP packet: [16, {"index": 0, "count": 2, "data": {"
Dec 17 19:39:04 KoboUNCaGED[18271]: 2020/12/17 19:39:04 [DEBUG] Read TCP packet: [16, {"index": 1, "count": 2, "data": {"
Dec 17 19:39:05 KoboUNCaGED[18271]: 2020/12/17 19:39:05 [DEBUG] Read TCP packet: [5, {}]
Dec 17 19:39:05 KoboUNCaGED[18271]: 2020/12/17 19:39:05 [DEBUG] Calibre Opcode received: 5
Dec 17 19:39:05 KoboUNCaGED[18271]: 2020/12/17 19:39:05 [DEBUG] Processing FREE_SPACE packet: {}
Dec 17 19:39:05 KoboUNCaGED[18271]: 2020/12/17 19:39:05 [DEBUG] Wrote TCP packet: 39[0,{"free_space_on_device":1156497408}
Dec 17 19:39:05 KoboUNCaGED[18271]: 2020/12/17 19:39:05 [DEBUG] Read TCP packet: [12, {}]
Dec 17 19:39:05 KoboUNCaGED[18271]: 2020/12/17 19:39:05 [DEBUG] Calibre Opcode received: 12
Dec 17 19:39:05 KoboUNCaGED[18271]: 2020/12/17 19:39:05 [DEBUG] Processing NOOP packet: {}
Dec 17 19:39:05 KoboUNCaGED[18271]: 2020/12/17 19:39:05 [DEBUG] Wrote TCP packet: 6[0,{}]
Dec 17 19:39:07 KoboUNCaGED[18271]: 2020/12/17 19:39:07 [DEBUG] Read TCP packet: [12, {}]
Dec 17 19:39:07 KoboUNCaGED[18271]: 2020/12/17 19:39:07 [DEBUG] Calibre Opcode received: 12
Dec 17 19:39:07 KoboUNCaGED[18271]: 2020/12/17 19:39:07 [DEBUG] Processing NOOP packet: {}
Dec 17 19:39:07 KoboUNCaGED[18271]: 2020/12/17 19:39:07 [DEBUG] Wrote TCP packet: 6[0,{}]
Dec 17 19:39:09 KoboUNCaGED[18271]: 2020/12/17 19:39:09 [DEBUG] Read TCP packet: [12, {}]
Dec 17 19:39:09 KoboUNCaGED[18271]: 2020/12/17 19:39:09 [DEBUG] Calibre Opcode received: 12
Dec 17 19:39:09 KoboUNCaGED[18271]: 2020/12/17 19:39:09 [DEBUG] Processing NOOP packet: {}
Dec 17 19:39:09 KoboUNCaGED[18271]: 2020/12/17 19:39:09 [DEBUG] Wrote TCP packet: 6[0,{}]
Dec 17 19:39:11 KoboUNCaGED[18271]: 2020/12/17 19:39:11 [DEBUG] Read TCP packet: [12, {}]
Dec 17 19:39:11 KoboUNCaGED[18271]: 2020/12/17 19:39:11 [DEBUG] Calibre Opcode received: 12
Dec 17 19:39:11 KoboUNCaGED[18271]: 2020/12/17 19:39:11 [DEBUG] Processing NOOP packet: {}
Dec 17 19:39:11 KoboUNCaGED[18271]: 2020/12/17 19:39:11 [DEBUG] Wrote TCP packet: 6[0,{}]
Dec 17 19:39:13 KoboUNCaGED[18271]: 2020/12/17 19:39:13 [DEBUG] Read TCP packet: [12, {}]
Dec 17 19:39:13 KoboUNCaGED[18271]: 2020/12/17 19:39:13 [DEBUG] Calibre Opcode received: 12
Dec 17 19:39:13 KoboUNCaGED[18271]: 2020/12/17 19:39:13 [DEBUG] Processing NOOP packet: {}
Dec 17 19:39:13 KoboUNCaGED[18271]: 2020/12/17 19:39:13 [DEBUG] Wrote TCP packet: 6[0,{}]
Dec 17 19:39:15 KoboUNCaGED[18271]: 2020/12/17 19:39:15 [DEBUG] Read TCP packet: [12, {}]
Dec 17 19:39:15 KoboUNCaGED[18271]: 2020/12/17 19:39:15 [DEBUG] Calibre Opcode received: 12
Dec 17 19:39:15 KoboUNCaGED[18271]: 2020/12/17 19:39:15 [DEBUG] Processing NOOP packet: {}
Dec 17 19:39:15 KoboUNCaGED[18271]: 2020/12/17 19:39:15 [DEBUG] Wrote TCP packet: 6[0,{}]
Dec 17 19:39:25 KoboUNCaGED[18271]: 2020/12/17 19:39:25 [DEBUG] Read TCP packet: [12, {}]
Dec 17 19:39:25 KoboUNCaGED[18271]: 2020/12/17 19:39:25 [DEBUG] Calibre Opcode received: 12
Dec 17 19:39:25 KoboUNCaGED[18271]: 2020/12/17 19:39:25 [DEBUG] Processing NOOP packet: {}
Dec 17 19:39:25 KoboUNCaGED[18271]: 2020/12/17 19:39:25 [DEBUG] Wrote TCP packet: 6[0,{}]
Dec 17 19:39:35 KoboUNCaGED[18271]: 2020/12/17 19:39:35 [DEBUG] Read TCP packet: [12, {}]
Dec 17 19:39:35 KoboUNCaGED[18271]: 2020/12/17 19:39:35 [DEBUG] Calibre Opcode received: 12
Dec 17 19:39:35 KoboUNCaGED[18271]: 2020/12/17 19:39:35 [DEBUG] Processing NOOP packet: {}
Dec 17 19:39:35 KoboUNCaGED[18271]: 2020/12/17 19:39:35 [DEBUG] Wrote TCP packet: 6[0,{}]
Dec 17 19:39:45 KoboUNCaGED[18271]: 2020/12/17 19:39:45 [DEBUG] Read TCP packet: [12, {}]
Dec 17 19:39:45 KoboUNCaGED[18271]: 2020/12/17 19:39:45 [DEBUG] Calibre Opcode received: 12
Dec 17 19:39:45 KoboUNCaGED[18271]: 2020/12/17 19:39:45 [DEBUG] Processing NOOP packet: {}
Dec 17 19:39:45 KoboUNCaGED[18271]: 2020/12/17 19:39:45 [DEBUG] Wrote TCP packet: 6[0,{}]
Dec 17 19:39:55 KoboUNCaGED[18271]: 2020/12/17 19:39:55 [DEBUG] Read TCP packet: [12, {}]
Dec 17 19:39:55 KoboUNCaGED[18271]: 2020/12/17 19:39:55 [DEBUG] Calibre Opcode received: 12
Dec 17 19:39:55 KoboUNCaGED[18271]: 2020/12/17 19:39:55 [DEBUG] Processing NOOP packet: {}
Dec 17 19:39:55 KoboUNCaGED[18271]: 2020/12/17 19:39:55 [DEBUG] Wrote TCP packet: 6[0,{}]
Dec 17 19:40:05 KoboUNCaGED[18271]: 2020/12/17 19:40:05 [DEBUG] Read TCP packet: [12, {}]
Dec 17 19:40:05 KoboUNCaGED[18271]: 2020/12/17 19:40:05 [DEBUG] Calibre Opcode received: 12
Dec 17 19:40:05 KoboUNCaGED[18271]: 2020/12/17 19:40:05 [DEBUG] Processing NOOP packet: {}
Dec 17 19:40:05 KoboUNCaGED[18271]: 2020/12/17 19:40:05 [DEBUG] Wrote TCP packet: 6[0,{}]
...
Dec 17 19:45:07 KoboUNCaGED[18271]: 2020/12/17 19:45:07 [DEBUG] Read TCP packet: [12, {}]
Dec 17 19:45:07 KoboUNCaGED[18271]: 2020/12/17 19:45:07 [DEBUG] Calibre Opcode received: 12
Dec 17 19:45:07 KoboUNCaGED[18271]: 2020/12/17 19:45:07 [DEBUG] Processing NOOP packet: {}
Dec 17 19:45:07 KoboUNCaGED[18271]: 2020/12/17 19:45:07 [DEBUG] Wrote TCP packet: 6[0,{}]
Dec 17 19:45:17 KoboUNCaGED[18271]: 2020/12/17 19:45:17 [DEBUG] Read TCP packet: [12, {}]
Dec 17 19:45:17 KoboUNCaGED[18271]: 2020/12/17 19:45:17 [DEBUG] Calibre Opcode received: 12
Dec 17 19:45:17 KoboUNCaGED[18271]: 2020/12/17 19:45:17 [DEBUG] Processing NOOP packet: {}
Dec 17 19:45:17 KoboUNCaGED[18271]: 2020/12/17 19:45:17 [DEBUG] Wrote TCP packet: 6[0,{}]