Frequently outdated feed

[traines-source]

Since I don't know which of the components is responsible for this issue, I decided to open it here. I hope this is ok, otherwise please lmk.

Frequently (multiple times a day) the GTFS-RT feed does not seem to get any updates, ranging from a couple of minutes to many hours. For instance, today, the feed received no update between 06:26 and 09:04 and then again between 09:12 and 09:26 (at least the Last-Modified header and the size of the feed did not change in these timespans):

Time of fetch              Last-Modified GMT  Size of feed pbf
2025-01-12T06:20:01+01:00  12-Jan-2025 05:19  5528811
2025-01-12T06:22:01+01:00  12-Jan-2025 05:22  5548269
2025-01-12T06:24:01+01:00  12-Jan-2025 05:24  5557671
2025-01-12T06:26:01+01:00  12-Jan-2025 05:25  5587035
2025-01-12T06:28:01+01:00  12-Jan-2025 05:27  5591552
2025-01-12T06:30:01+01:00  12-Jan-2025 05:27  5591552
2025-01-12T06:32:01+01:00  12-Jan-2025 05:27  5591552
2025-01-12T06:34:01+01:00  12-Jan-2025 05:27  5591552
2025-01-12T06:36:01+01:00  12-Jan-2025 05:27  5591552
[...]
2025-01-12T08:52:01+01:00  12-Jan-2025 05:27  5591552
2025-01-12T08:54:01+01:00  12-Jan-2025 05:27  5591552
2025-01-12T08:56:01+01:00  12-Jan-2025 05:27  5591552
2025-01-12T08:58:01+01:00  12-Jan-2025 05:27  5591552
2025-01-12T09:00:01+01:00  12-Jan-2025 05:27  5591552
2025-01-12T09:02:02+01:00  12-Jan-2025 05:27  5591552
2025-01-12T09:04:01+01:00  12-Jan-2025 08:04  4683048
2025-01-12T09:06:01+01:00  12-Jan-2025 08:06  5480830
2025-01-12T09:08:01+01:00  12-Jan-2025 08:08  6264562
2025-01-12T09:10:01+01:00  12-Jan-2025 08:10  6976197
2025-01-12T09:12:01+01:00  12-Jan-2025 08:10  7104117
2025-01-12T09:14:01+01:00  12-Jan-2025 08:10  7104117
2025-01-12T09:16:01+01:00  12-Jan-2025 08:10  7104117
2025-01-12T09:18:01+01:00  12-Jan-2025 08:10  7104117
2025-01-12T09:20:01+01:00  12-Jan-2025 08:10  7104117
2025-01-12T09:22:01+01:00  12-Jan-2025 08:10  7104117
2025-01-12T09:24:01+01:00  12-Jan-2025 08:10  7104117
2025-01-12T09:26:01+01:00  12-Jan-2025 08:26  7173713
2025-01-12T09:28:01+01:00  12-Jan-2025 08:28  7208802
2025-01-12T09:30:01+01:00  12-Jan-2025 08:30  7230522
2025-01-12T09:32:01+01:00  12-Jan-2025 08:32  7238674

I cannot imagine that during these timespans, actually no realtime data changed, so I suppose updates are missing from the feed. Also see the subdirectories of https://stc.traines.eu/mirror/vbb-gtfs-rt/ for the respective records of the current and previous day.

[derhuerst]

Thanks for reporting this.

There are two possible reasons for why up-to-date realtime data is missing from the feed:

1. If the fetching of VDV-453/-454 messages fails, then there won't be any realtime data to process.
2. VDV-453/-454 messages that can't be matched will be discarded. So if, by chance, all messages in a while can't be matched, the GTFS-RT feed won't get an update. However, it is highly unlikely that all VDV messages can't be matched for hours.

In the first timeframe documented above (2025-01-12T06:30+01:00 until 2025-01-12T09:04+01:00), indeed no VDV-453/-454 data could be fetched:

I'll try to clarify with @OpenDataVBB/gtfs-rt what the cause is and if we can change anything about this.