Commit Graph

814 Commits (4fb8548aba150dfb3c631c36702d3723e2f0b79c)
 

Author SHA1 Message Date
Mike Lang 10cca18922 Fix a deadlock due to signal interactions with prometheus client
The prometheus client uses a threading.Lock() to prevent shared access to
certain metric state. This lock is taken as part of doing collection, as well
as during metric.labels().

We hit a deadlock where our stack sampler signal arrived during a collection,
when the lock was held. This meant that flamegraph.labels() blocked forever,
and the lock was never released, hanging all metrics collection.

Our solution is a hack, which is to reach into the internals of our metric object
and replace its lock with a dummy one. This is reasonably safe, but only as long as
the prometheus_client internal structure doesn't change signfigiantly.
6 years ago
Mike Lang c9cc8a73a7 generate-flamegraph: Script to create a flamegraph by querying prometheus 6 years ago
Mike Lang b75b9a9b00 Add stacksampler to all services 6 years ago
Mike Lang b9c2921242 common.stats: Add a stacksampler that records sampled stacks to prometheus
This can then be used to generate flamegraphs
6 years ago
Mike Lang a5213ccb3b downloader: Pool connections when we can
To preserve independence between workers and ensure that a
retry (a worker re-create) actually starts from scratch, we only pool connections
on a per-worker basis.
Furthermore, for the same reason, we only let SegmentGetters use the worker's
pool on their first attempt. After that, they create a new pool to ensure they have a clean retry.

Despite this, the result should be that we're almost always re-using an existing connection
when getting segments or media playlists, unless something goes wrong.

SSL connection setup was measured as almost half the CPU time used by the process,
so this change should result in a signifigant CPU usage reduction.
6 years ago
Mike Lang 5175b099af common: Split segment-related stuff into its own module
We still import them into __init__.py so they're accessible externally just the same
6 years ago
Mike Lang 6f84a23ba6 common: Split stats-related stuff into its own module
We still import them into __init__.py so they're accessible externally just the same
6 years ago
Mike Lang 8fe2fec958 common: convert from module to package 6 years ago
MasterGunner 96c1566d21
Merge pull request #34 from ekimekim/gunner/restreamer/additional-routes
Added additional routes for listing available streams and variants.
6 years ago
MasterGunner a9569d9e96 Removed unneeded '@has_path_args'. 6 years ago
MasterGunner 306ac53d08 Added additional routes for listing available streams and variants. 6 years ago
Mike Lang 901cda4814 Enable backdoor in all services, and add telnet to containers 6 years ago
Mike Lang 9af7795f34 Add gevent.backdoor as an optional arg to all services
Backdoor allows the operator to telnet into the given port, and get a python shell
running inside the process, from which you can debug, modify state (eg. set the log level),
or whatever. This is extremely useful for debugging weird states that you encounter randomly
but can't easily reproduce, without restarting the process and needing to wait until it happens again.
6 years ago
Mike Lang 47ff92b155 downloader: Fix bug where mark_working wasn't called
This meant that old workers would never shut down, causing us to fetch the same media playlist
and same segments multiple times for no reason, and to never give up in face of (non-403/404) errors
even once we have something else working.
6 years ago
Mike Lang 3042d00516 downloader: Give up on 404 in addition to 403
Also fix some logging.

When we're out of touch with twitch for long enough, our segment URL will get
so old that twitch stops returning 403 because our token is expired,
and start returning 404s, presumebly becasue the underlying resource has gone away.

We want to treat these the same.
6 years ago
Mike Lang 7f9a1dbe45 downloader: Remove implicit source quality arg
This brings it in line with backfiller, is more flexible and less surprising
6 years ago
Mike Lang 89d6b3a6be docker-compose: Add list of peers to backfill from 6 years ago
Mike Lang 0d627715f3 downloader: Track number of downloaded segments
This is the most important metric, we can add more later.
6 years ago
Mike Lang 90ccc6d827 backfiller: Track number of successful backfills
Other stats can come later, but this one is important as it tells us if
a downloader hasn't been doing its job.
6 years ago
Mike Lang c59892e148 backfiller: Add ability to set nodes as CLI arg 6 years ago
Mike Lang bdcb217d20 docker-compose: Expose metrics ports for other services 6 years ago
Mike Lang b4b315b6bc Expose prometheus metrics for backfiller and downloader 6 years ago
Mike Lang d90f01b8ce common: Create general function for timing things, and use it to time get_best_segments
The function is quite customizable and therefore quite complex, but it allows us to
easily annotate a function to be timed with labels based on input and output,
as well as normalize results based on amount of work done to get a better
picture of the actual amount of time taken per unit of work.
This will help us monitor for performance issues.
6 years ago
Mike Lang b0ded641c3 Add a logging handler which counts logs for prometheus stats
This isn't as good as having a full centralised logging system, but should
suffice to know if anything funny is happening.
6 years ago
Mike Lang c9d02b3318 restreamer: Prevent prom client blowing up after two different endpoints are hit
Prom client doesn't like you creating two stats with the same name,
even though they have different labels and this makes perfect sense.

I feel like I just need to re-write the prom client at some point - it doesn't actually
do all that much except get in your way, apart from the actual text encoding which I
can steal.

Anyway, in the meantime, we get around this by breaking up metrics into two names,
a "foo_all" and a "foo_ENDPOINT". The foo_all lacks the detailed labels,
but is still labelled by endpoint and can be used more easily.
The foo_ENDPOINT labels have more information but require messier PromQL as you need to
match on a name regex if you want to look at more than one specific endpoint.
6 years ago
Mike Lang 30c4bbec1d restreamer: return the actual response from after_request even if untracked
otherwise any untracked endpoints don't work
6 years ago
Christopher Usher 96e6904c85 Added monotonic to restreamer setup.py 6 years ago
Christopher Usher 225288980a Added the backfiller to docker-compose 6 years ago
Christopher Usher 3fcd374449 Moved encode_strings to common 6 years ago
Christopher Usher 93dd216f89 Fixes and suggestions from ekimekim 6 years ago
Christopher Usher db1b4e6539 Updated logging to match the other components 6 years ago
Christopher Usher bae039977b trying getting the backfiller to actually start 6 years ago
Christopher Usher 1fcd9b5b36 Adding in stuff to hopefully get this to run 6 years ago
Christopher Usher 013ad65c68 added a Dockerfile for the backfiller 6 years ago
Christopher Usher 48d11045d4 Change to backfiller.main to backfill the last 3 hours on start up before doing a full backfill 6 years ago
Christopher Usher 176633bf7d More messing around with backfill_node to allow finer grained control of order segments are fetched 6 years ago
Christopher Usher 3a7624b107 added a setup file for the backfiller 6 years ago
Christopher Usher ba499fe835 added more logging to backfiller 6 years ago
Mike Lang 7525b7c135 restreamer: Add basic prometheus stats to all endpoints
I had to go to some effort to get nice labelling,
which also meant none of the existing libs for this were any good,
but this works well enough.

Exposes the metrics on /metrics.
6 years ago
Mike Lang 17972b87aa Allow setting of log level via WUBLOADER_LOG_LEVEL env var
By using an env var, it is universal and happens prior to arg parsing,
at the same point we do other logging setup.
6 years ago
Mike Lang c0357680cf downloader: Use caller's logger inside soft_hard_timeout 6 years ago
Mike Lang a628676e74 downloader: Log to subloggers instead of the root logger
This gives us some context when logging, and is best practice.
6 years ago
Mike Lang 57e665df2e generate-docker-compose: Clean up the container afterwards
I'll never understand why this isn't the default, docker.
6 years ago
Mike Lang c8cc4a68a0 cutter: Fix bugs that meant things wouldn't actually be cut
The calculations were backwards, so instead of cutting a video by, say, 2 seconds,
it would cut by -2 seconds, which was clamped to 0. So it would never actually cut,
it would always use the closest segment.

Also, once we were actually cutting, we hit an issue where ffmpeg would finish and close
its input early, because we'd reached the end of the cut video, but not all input had been written yet.
This resulted in an EPIPE error (write to closed pipe) in the input feeder. We now ignore that.
6 years ago
Mike Lang 6bf709287a cutter: Introduce an alternate cutting approach that is much faster
This cutter works by only cutting the first and last segments to size,
then concatting them with the other segments, so we only ever process a few seconds
of video instead of the entire video duration.
However, to make this work, care must be taken that the cut segments use the same codecs
as the other segments.

The reason it's experimental is that we are not yet confident in its ability
to cut accurately and without sync issues. We have seen some minor issues when trying to play
back the raw output files, but youtube's re-encoding has consistently smoothed out those issues
and they seem to be highly player-specific. Vigorous testing is needed.

Also note that both methods right now (cat then cut, and cut then cat) only work if all the segments
are cattable, that is they all use the same codecs, have the same resolution, etc.
If a stream were to change its encoding settings, and we were cutting over that change,
both approaches would not work. We should add checks for that scenario (which can only happen
over a stream drop), and if so fallback to a slow method using ffmpeg's concat filter,
which will work even for disparate codecs, though reconciling mismatched resolutions or frame rates
may require further work.
6 years ago
Mike Lang 6815924097 Fix some bugs and linter errors introduced by backfiller
I ran `pyflakes` on the repo and found these bugs:

```
./common/common.py:289: undefined name 'random'
./downloader/downloader/main.py:7: 'random' imported but unused
./backfiller/backfiller/main.py:150: undefined name 'variant'
./backfiller/backfiller/main.py:158: undefined name 'timedelta'
./backfiller/backfiller/main.py:171: undefined name 'sort'
./backfiller/backfiller/main.py:173: undefined name 'sort'
```
(ok, the "imported but unused" one isn't a bug, but the rest are)

This fixes those, as well as a further issue I saw with sorting of hours.

Iterables are not sortable. As an obvious example, what if your iterable was infinite?
As a result, any attempt to sort an iterable that is not already a friendly type like a list
or tuple will result in an error. We avoid this by coercing to list, fully realising the iterable
and putting it into a form that python will let us sort. It also avoids the nasty side-effect
of mutating the list that gets passed into us, which the caller may not expect. Consider this example:

```
>>> my_hours = ["one", "two", "three"]
>>> print my_hours
["one", "two", "three"]
>>> backfill_node(base_dir, node, stream, variants, hours=my_hours, order='forward')
>>> print my_hours
["one", "three", "two"]
```

Also, one of the linter errors was non-trivial to fix - we were trying to get a list of hours
(which is an api call for a particular variant), but at a time when we weren't dealing with a single
variant. My solution was to get a list of hours for ALL variants, and take the union.
6 years ago
Mike Lang 78a9a4e525 Set up a docker compose file to run all images
For ease-of-use, we use a jsonnet file to generate the yaml.
Jsonnet is a language for generating JSON documents.

In this case it's useful to us because it lets us have comments,
references to settings defined at the top, and some basic logic
like converting qualities from a list of strings to a comma-seperated string.

To avoid requiring jsonnet to be installed, we use the official jsonnet docker image
in the generate script.
6 years ago
Mike Lang 25185f8f1f travis.yml: Make script into individual lines
Setting -eu fucks up travis's scripts, so instead we should feed it everything
command-by-command so it can fail out using its own logic.
6 years ago
Mike Lang 4dc00052f6 Add .travis.yaml to set up CI
Nothing fancy, just build the images and push them,
and if it's a push to master then also build latest.
6 years ago
Mike Lang 18aadd6b82 restreamer: Also have an endpoint for generating cut videos on demand
This is mainly just for testing until we get the database and proper cutter up,
but it might prove useful to have in the long run too.

This code will probably end up being totally rewritten,
as it uses the most naive form of cutting and reencoding,
and it has a whole bunch of http-serving specifics intertwined with the cutting logic.
6 years ago