[ensembl-dev] Noticing very slow requests on `rest.ensemble.org`

[Kat Salameh]

Hello,

We use the ensembl REST API to look up genome data in our application,
typically at the rate of a few requests per minute at most. We've noticed
recently that requests to `rest.ensembl.org` have been taking an
exceptionally long time. Specifically, since about 21:00 UTC on February
16, we've been seeing over half of requests to any `rest.ensembl.org`
endpoint take more than 30 seconds. There aren't any changes to the
statuses or other data returned that I can see, just that requests have
suddenly begun to take an extremely long time.

I tried testing on my laptop with `curl` to see if I could reproduce the
issue, and it did happen when I tried to use the same user agent string as
our script/application.
For example:
-The command `curl https://rest.ensembl.org/info/assembly/homo_sapiens\ -H
"Content-Type: application/json"` returns a result from the server in less
than a second from my laptop, which is what I would expect.
- Using the same user agent as my laptop's Chrome browser has the same
result.
- However, if I add `-A "python-requests/2.32.4"` to that curl command,
mimicking the python requests user agent we use for programmatic access in
our application, the same request now takes between 45-120 seconds or more.

Did anything change about the configuration of `rest.ensembl.org` that
might be causing requests to be delayed by 10s of seconds? Should we change
how we're requesting data from `rest.ensembl.org` to address this issue?
Any guidance would be appreciated. Thank you!

Best,
Kat Salameh
Software Engineer at Benchling
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