Howard Yoo created HADOOP-15230:
-----------------------------------
Summary: org.apache.hadoop.metrics2.GraphiteSink is not
implemented correctly
Key: HADOOP-15230
URL: https://issues.apache.org/jira/browse/HADOOP-15230
Project: Hadoop Common
Issue Type: Bug
Components: metrics
Reporter: Howard Yoo
org.apache.hadoop.metrics2.GraphiteSink's implementation has certain problems
that would make it to generate metrics incorrectly.
The problem lies with line 77 ~ 84 of the GraphiteSink java:
{code:java}
for (MetricsTag tag : record.tags()) {
if (tag.value() != null) {
metricsPathPrefix.append(".");
metricsPathPrefix.append(tag.name());
metricsPathPrefix.append("=");
metricsPathPrefix.append(tag.value());
}
}
{code}
It produces point tags having name=value pair in the metrics. However, notice
how the tags are added with '.' as its delimiters. Rather than using the '.'
character, it should follow the following convention mentioned in the latest
graphite doc of using ';' character.
[http://graphite.readthedocs.io/en/latest/tags.html]
Also, the value is not properly being escaped, meaning that if the value has a
'.' character in it, it will easily confuse Graphite to accept it as a
delimiter, rather than the value. A really good prime example is when the value
is a hostname or ip address,
{code:java}
metrics.example.Hostname=this.is.a.hostname.and.this.is.Metrics 10.0{code}
In this example, the since the value of the hostname contains '.', it is
extremely hard for the receiving end to determine which part is hostname and
which part is the rest of the metrics name. A good strategy is to convert any
'.' character in the value to be converted to other characters, such as '_'.
However, the best way would be to follow the latest metrics convention of using
';'
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