If a given pidFn for a process collector can't determine the pid, this
had to be signaled with an invalid pid so far (pid <= 0). In order to
make the error interface clearer for users, this change introduces an
explicit error parameter.
Adjust the API and usage accordingly.
Make tests stricter.
Since the merging is still faulty, test are broken now.
The next commit will fix it by avoiding merging.
Summaries as implemented cannot be aggregated in a meaningful
way. Partitoning them by status code and method only made sense if we
were interested in the individual latency and size of e.g. GET request
that result in status 503. In general, that's not the case. Most of
the time, the user will be interested in the latency and size of _all_
HTTP requests.
(With future changes to client_golang, we will consider making the
HTTP instrumentation configurable, e.g. to handle the case where the
user is only interested in the latency of successful requests.)
Both are interface changes I want to get in before public
announcement. They only break rare usage cases, and are always easy to
fix, but still we want to avoid breaking changes after a wider
announcement of the project.
The change of Register() simply removes the return of the Collector,
which nobody was using in practice. It was just bloating the call
syntax. Note that this is different from RegisterOrGet(), which is
used at various occasions where you want to register something that
might or might not be registered already, but if it is, you want the
previously registered Collector back (because that's the relevant
one).
WRT error reporting: I first tried the obvious way of letting the
Collector methods Describe() and Collect() return error. However, I
had to conclude that that bloated _many_ calls and their handling in
very obnoxious ways. On the other hand, the case where you actually
want to report errors during registration or collection is very
rare. Hence, this approach has the wrong trade-off. The approach taken
here might at first appear clunky but is in practice quite handy,
mostly because there is almost no change for the "normal" case of "no
special error handling", but also because it plays well with the way
descriptors and metrics are handled (via channels).
Explaining the approach in more detail:
- During registration / describe: Error handling was actually already
in place (for invalid descriptors, which carry an error anyway). I
only added a convenience function to create an invalid descriptor
with a given error on purpose.
- Metrics are now treated in a similar way. The Write method returns
an error now (the only change in interface). An "invalid metric" is
provided that can be sent via the channel to signal that that metric
could not be collected. It alse transports an error.
NON-GOALS OF THIS COMMIT:
This is NOT yet the major improvement of the whole registry part,
where we want a public Registry interface and plenty of modular
configurations (for error handling, various auto-metrics, http
instrumentation, testing, ...). However, we can do that whole thing
without breaking existing interfaces. For now (which is a significant
issue) any error during collection will either cause a 500 HTTP
response or a panic (depending on registry config). Later, we
definitely want to have a possibility to skip (and only report
somehow) non-collectible metrics instead of aborting the whole scrape.
This change adds two new collectors to the prometheus package which
export metrics about a given or the current process.
* ProcessCollector exports metrics about cpu time, vss, rss, fd usage as
well as the start time of a given process.
* GoCollector exports currently only the number of active goroutines.
computeApproximateRequestSize is run in a goroutine, but the
handlerFunc that runs in parallel may modify the URL, which is also
needed by computeApproximateRequestSize. So get the URL length
beforehand.
Change-Id: Idb84735845afe7be4ef79b3d642d5764f6d26a7c
Also, remove quotes from the Content-type header. It's not illegal to
have quotes there, but they are not needed, and at other places, we
are not using them. So fewer characters and more consistency.
Change-Id: If7a78bde85154163e4426daec493d973213e83e9
Since we prepare the whole content in a buf before sending, we can as
well set the Content-Length explicitly.
Change-Id: Ifd91764c90af53be49f93f0b33032138130b6f96
This is actually the intended behavior, and (as a nice side effect)
makes things cheaper to calculate.
Also, introduce a separator character to avoid hash collisions
(like label values {"ab","c"} vs {"a", "bc"}).
Apply the same principles to signature.go.
Change-Id: I607db544f278ed89684fe5fa11abdbc3e03d3061
Also, fix seconds to microseconds fot the http instrumentation to
match the metric name.
Fix Desc.String().
Simplify http error display.
Change-Id: Ib7397f4eac1eeed92b291e1c9cc88c080aee99ca
This rewrite had may backs and forths. In my git repository, it
consists of 35 commits which I cannot group or merge into reasonable
review buckets. Gerrit breaks fundamental git semantics, so I have to
squash the 35 commits into one for the review.
I'll push this not with refs/for/master, but with refs/for/next so
that we can transition after submission in a controlled fashion.
For the review, I recommend to start with looking at godoc and in
particular the many examples. After that, continue with a line-by-line
detailed review. (The big picture is hopefully as expected after
wrapping up the discussion earlier.)
Change-Id: Ib38cc46493a5139ca29d84020650929d94cac850
Most important here is the simple & flat text format, but while I'm on
it, I have also added the text representations for protobufs (which is
purely meant for debugging purposes). I hope my basic idea about
handling those various protocols (and the text package) becomes
clearer now.
Change-Id: I7299853eadc82a426101e907f2b3d4e37f9e4c71
The LabelsToSignature function is now used outside of the prometheus
package, too. Leaving it in the prometheuos package is misleading
design and will lead to circulat import chains soon.
Change-Id: If1ca442d4023b33b138cf79fee68e82ff2a355be
- Full support for UNTYPED type.
- Receptive support for timestamp_ms (i.e. the processor can process
it, but the client library cannot yet create it - which is kind of
intended as timestamps are meant for other things like federation,
which will need separate support anyway).
Change-Id: I5913164a80089943d49ad58bf86e465a843ab82b
The idea here is to always go via the protobufs if dealing with the
text format. That won't always be the most efficient way, but it
avoids the multiplicity of conversion routines required for direct
conversion (e.g. text format -> internal representation in the
Prometheus server). The loss of efficiency is acceptable because the
text format should not be used in high performance (high throughput,
low latency) situations anyway.
In that way, the text format stays perfectly isolated from other parts
of the code. To receive text format, just plug the conversion in
before the code path that normally reads protobufs. Correspondingly,
for sending text format, simply replace the WriteDelimited call by a
text.Create call.
Nevertheless, the conversion code itself is optimized for efficiency
and minimized memory churn (which was one of the reason for handcoding
the parser and not using a lexer/parser code generation tool).
Change-Id: Iee45ffe8aa421a844225d13a1f859becd8a3b066
These are all simple changes we should have caught a long time ago:
1. The hashing mechanism for fingerprint label sets should have not
allocated new objects for the actual hashing---at least not
egregiously. This simplifies the hash writing by just byte-
dumping the string stream into the hasher.
2. The hashing mechanism within the scope of a metric does not care
about the value of the label keys themselves but only of the label
values. The keys can be dropped from the calculation.
3. The locking mechanism for the metrics should not block on hash
computation but rather solely on the actual mutation or critical
section reads.
4. For scalar metrics (i.e., ones with niladic label signatures), we
should rely on a preallocated map versus requesting a new one
ad hoc.
This is tested with Go 1.1, so the results may yield other values
for us elsewhere:
BEFORE
BenchmarkLabelValuesToSignatureScalar 500000000 3.97 ns/op 0 B/op 0 allocs/op
BenchmarkLabelValuesToSignatureSingle 5000000 714 ns/op 74 B/op 4 allocs/op
BenchmarkLabelValuesToSignatureDouble 1000000 1153 ns/op 107 B/op 5 allocs/op
BenchmarkLabelValuesToSignatureTriple 1000000 1588 ns/op 138 B/op 6 allocs/op
BenchmarkLabelToSignatureScalar 500000000 3.91 ns/op 0 B/op 0 allocs/op
BenchmarkLabelToSignatureSingle 2000000 874 ns/op 92 B/op 5 allocs/op
BenchmarkLabelToSignatureDouble 1000000 1528 ns/op 139 B/op 7 allocs/op
BenchmarkLabelToSignatureTriple 1000000 2172 ns/op 186 B/op 9 allocs/op
AFTER
BenchmarkLabelValuesToSignatureScalar 500000000 4.36 ns/op 0 B/op 0 allocs/op
BenchmarkLabelValuesToSignatureSingle 5000000 378 ns/op 89 B/op 4 allocs/op
BenchmarkLabelValuesToSignatureDouble 5000000 574 ns/op 142 B/op 5 allocs/op
BenchmarkLabelValuesToSignatureTriple 5000000 758 ns/op 186 B/op 6 allocs/op
BenchmarkLabelToSignatureScalar 500000000 4.06 ns/op 0 B/op 0 allocs/op
BenchmarkLabelToSignatureSingle 5000000 472 ns/op 106 B/op 5 allocs/op
BenchmarkLabelToSignatureDouble 2000000 746 ns/op 174 B/op 7 allocs/op
BenchmarkLabelToSignatureTriple 1000000 1061 ns/op 235 B/op 9 allocs/op
In effect, a single metric mutation operation's lookup overhead will
move from Before::iBenchmarkLabelToSignature to
After::BenchmarkLabelValuesToSignature. This MINIMALLY reduces
1/2 the overhead. I would be hesitant in reading the memory
allocation statistics, for this was run with the GC still on and
thusly inaccurate per Go benchmarking documentation.
Before::BenchmarkLabelValuesToSignature never existed, so it is not
of any intrinsic value in itself. That said, the cases that still
rely on LabelToSignature experience consistently a 1/2 drop in time.
Change-Id: Ifc9e69f718af65a59f5be8117473518233258159
This hook is needed for the upcoming push gateway.
Also remove go vet warnings and add test for Handler().
Change-Id: If6c56676c7a0f10c16b4effae7285903f8267616
This also adds a check that forbids any user-supplied metrics to start
with the reserved label name prefix "__".
Change-Id: I2fe94c740b685ad05c4c670613cf2af7b9e1c1c0
This is an optimization of labelsToSignature to avoid excess allocations
when the label set is empty.
Change-Id: If2d59bbc3ae6d4457e2ded197b6f4e7c67e6a173
This ensures that you can pass the same base label set into multiple
Register() calls, e.g.:
labels := map[string]string{"key": "value"}
prometheus.Register("metric_1", "", labels, ...)
prometheus.Register("metric_2", "", labels, ...)
Change-Id: I951e5c2ed7844c74eb3716d1bf07126ce558f266
Tobias Schmidt