Currently all read queries are simply pushed to remote read clients.
This is fine, except for remote storage for wich it unefficient and
make query slower even if remote read is unnecessary.
So we need instead to compare the oldest timestamp in primary/local
storage with the query range lower boundary. If the oldest timestamp
is older than the mint parameter, then there is no need for remote read.
This is an optionnal behavior per remote read client.
Signed-off-by: Thibault Chataigner <t.chataigner@criteo.com>
Instead or only printing the help message, which is not always helpful.
For example, when upgrading from prometheus v1, the retention time value
format has changed and now only accepts one unit (e.g. "15d") where it
previously allowed more complex strings (e.g. "360h0m0s").
This commit provides the error message as an explanation for the parsing
failure.
The usage of govalidator is redundant with the call to url.Parse for
url validation. Removing it has the following benefits:
- The explicit error message is displayed instead of just a generic
valid/invalid message
- Slightly smaller code with one fewer external dependency
- Speed improvement by removing duplicate call to url.Parse (inside
govalidator.IsURL()
- Resolves issue #2717
The only potential drawback of removing govalidator is that certain
URLs will be considered valid which were previously invalid. For example:
- URLs with hostnames that start and/or end with an underscore (http://_example.com_)
- URLs with hostnames that contain some special characters (http://foo&*bar.org)
These are valid URIs according to RFC 3986 and valid domain names per RFC 2181,
however they are not valid hostnames per RFC 952.
Whenever a route prefix is applied, the router prepends the prefix to
the URL path on the request. For most handlers, this is not an issue
because the request's path is only used for routing and is not actually
needed by the handler itself. However, Prometheus delegates the handling
of the /debug/* endpoints to the http.DefaultServeMux which has it's own
routing logic that depends on the url.Path. As a result, whenever a
prefix is applied, the prefixed URL is passed to the DefaultServeMux
which has no awareness of the prefix and returns a 404.
This change fixes the issue by creating a new serveDebug handler which
routes requests /debug/* requests to appropriate net/http/pprof handler
and removing the net/http/pprof import in cmd/prometheus since it is no
longer necessary.
Fixes#2183.
* Move fingerprint to Hash()
* Move away from tsdb.MultiError
* 0777 -> 0666 for files
* checkOverflow of extra fields
Signed-off-by: Goutham Veeramachaneni <cs14btech11014@iith.ac.in>
* Print uname on prom startup
* Make uname file linux-only
* Add missing license headers
Add missing license headers
* Print OS when uname is not available
* Print only OS name when uname not available
* Remove extra space, fix cmd/prometheus/main.go license header
* Add fix for int8 and uint8 systems
* Better formatting for build tags in cmd/prometheus/uname files
* Remove newline
This is a fairly easy attempt to dynamically evict chunks based on the
heap size. A target heap size has to be set as a command line flage,
so that users can essentially say "utilize 4GiB of RAM, and please
don't OOM".
The -storage.local.max-chunks-to-persist and
-storage.local.memory-chunks flags are deprecated by this
change. Backwards compatibility is provided by ignoring
-storage.local.max-chunks-to-persist and use
-storage.local.memory-chunks to set the new
-storage.local.target-heap-size to a reasonable (and conservative)
value (both with a warning).
This also makes the metrics intstrumentation more consistent (in
naming and implementation) and cleans up a few quirks in the tests.
Answers to anticipated comments:
There is a chance that Go 1.9 will allow programs better control over
the Go memory management. I don't expect those changes to be in
contradiction with the approach here, but I do expect them to
complement them and allow them to be more precise and controlled. In
any case, once those Go changes are available, this code has to be
revisted.
One might be tempted to let the user specify an estimated value for
the RSS usage, and then internall set a target heap size of a certain
fraction of that. (In my experience, 2/3 is a fairly safe bet.)
However, investigations have shown that RSS size and its relation to
the heap size is really really complicated. It depends on so many
factors that I wouldn't even start listing them in a commit
description. It depends on many circumstances and not at least on the
risk trade-off of each individual user between RAM utilization and
probability of OOMing during a RAM usage peak. To not add even more to
the confusion, we need to stick to the well-defined number we also use
in the targeting here, the sum of the sizes of heap objects.
Currently, if a series stops to exist, its head chunk will be kept
open for an hour. That prevents it from being persisted. Which
prevents it from being evicted. Which prevents the series from being
archived.
Most of the time, once no sample has been added to a series within the
staleness limit, we can be pretty confident that this series will not
receive samples anymore. The whole chain as described above can be
started after 5m instead of 1h. In the relaxed case, this doesn't
change a lot as the head chunk timeout is only checked during series
maintenance, and usually, a series is only maintained every six
hours. However, there is the typical scenario where a large service is
deployed, the deoply turns out to be bad, and then it is deployed
again within minutes, and quite quickly the number of time series has
tripled. That's the point where the Prometheus server is stressed and
switches (rightfully) into rushed mode. In that mode, time series are
processed as quickly as possible, but all of that is in vein if all of
those recently ended time series cannot be persisted yet for another
hour. In that scenario, this change will help most, and it's exactly
the scenario where help is most desperately needed.
Rationale: The default value for GOGC is 100, i.e. a garbage collected
is initialized once as many heap space has been allocated as was in
use after the last GC was done. This ratio doesn't make a lot of sense
in Prometheus, as typically about 60% of the heap is allocated for
long-lived memory chunks (most of which are around for many hours if
not days). Thus, short-lived heap objects are accumulated for quite
some time until they finally match the large amount of memory used by
bulk memory chunks and a gigantic GC cyle is invoked. With GOGC=40, we
are essentially reinstating "normal" GC behavior by acknowledging that
about 60% of the heap are used for long-term bulk storage.
The median Prometheus production server at SoundCloud runs a GC cycle
every 90 seconds. With GOGC=40, a GC cycle is run every 35 seconds
(which is still not very often). However, the effective RAM usage is
now reduced by about 30%. If settings are updated to utilize more RAM,
the time between GC cycles goes up again (as the heap size is larger
with more long-lived memory chunks, but the frequency of creating
short-lived heap objects does not change). On a quite busy large
Prometheus server, the timing changed from one GC run every 20s to one
GC run every 12s.
In the former case (just changing GOGC, leave everything else as it
is), the CPU usage increases by about 10% (on a mid-size referenc
server from 8.1 to 8.9). If settings are adjusted, the CPU
consumptions increases more drastically (from 8 cores to 13 cores on a
large reference server), despite GCs happening more rarely, presumably
because a 50% larger set of memory chunks is managed now. Having more
memory chunks is good in many regards, and most servers are running
out of memory long before they run out of CPU cycles, so the tradeoff
is overwhelmingly positive in most cases.
Power users can still set the GOGC environment variable as usual, as
the implementation in this commit honors an explicitly set variable.
