graphite-dev team mailing list archive

[Dave Rawks <dave@xxxxxxxxxxx>]

Seems like the error in the trace is pretty self explanatory. What is 
the name of the metric you are sending? Some portion of your metric name 
(dbFilePath) must contain a null which is not allowed by 
os.path.exists(). Since the metric names are fully controlled by 
whatever program you are using to ingest metrics the problem is unlikely 
to be in the carbon-cache code.

It would be possible to do checking in MetricLineReceiver, 
MetricDatagramReceiver and MetricPickle Receiver; but I think this would 
incur an unnecessary performance penalty since it would hit once per 
datapoint received. Alternatively, the approach I think is correct, 
would be to modify writeCachedDataPoints in writer.py to check the 
metric name inside the 'if not dbFileExists:' block and raise a log 
event for invalid metric names AND pop the metrics out of cache at the 
same time. This would incur the check penalty only on attempted creation 
of bad metrics.

-Dave

On 08/16/2012 09:21 AM, Mike Wylie wrote:
> Question #205774 on Graphite changed:
> https://answers.launchpad.net/graphite/+question/205774
>
> Mike Wylie posted a new comment:
> I had a look at the code in the exception trace and had a
> though....would I be taking my life in my hands if I altered the file
> /opt/graphite/lib/carbon/writer.py, to send the metric to the log file,
> just before trying to look for its path?  This may give me an idea what
> it's failing to work with.
>
> Would I need to restart something for the code to take affect?
>
> I'm not a real python programmer, but I can understand the basics, I was
> thinking something along the lines of:
>
> def optimalWriteOrder():
>    "Generates metrics with the most cached values first and applies a soft rate limit on new metrics"
>    global lastCreateInterval
>    global createCount
>    metrics = MetricCache.counts()
>
>    t = time.time()
>    metrics.sort(key=lambda item: item[1], reverse=True) # by queue size, descending
>    log.msg("Sorted %d cache queues in %.6f seconds" % (len(metrics), time.time() - t))
>
>    for metric, queueSize in metrics:
>      if state.cacheTooFull and MetricCache.size < CACHE_SIZE_LOW_WATERMARK:
>        events.cacheSpaceAvailable()
> # ------------------------------------------------
> # my new piece of code
> #
>      log.msg("reviewing metric:"+metric)
> # ------------------------------------------------
>      dbFilePath = getFilesystemPath(metric)
>      dbFileExists = exists(dbFilePath)