system metrics reported by collector always have a length of 10

[at15]

Related #21

When using xkc to report system metrics, the series length is always 10. And the collector buffer 10 points for each series.

DEBU[0038] mem:data create new entry cpu.6.user in map pkg=k.s.mem 
DEBU[0038] mem:data create new entry cpu.total.nice in map pkg=k.s.mem 
DEBU[0038] mem:data create new entry cpu.2.system in map pkg=k.s.mem 

DEBU[0113] mem:data merge with existing series cpu.0.iowait pkg=k.s.mem 
DEBU[0113] length 10 pkg=k.s.mem 
DEBU[0113] mem:data merge with existing series cpu.5.irq pkg=k.s.mem 
DEBU[0113] length 10 pkg=k.s.mem 

But test in series_store_test.go shows it correctly handled merge data, one explanation could be the collector is using same time stamp

TODO

• write a test to reproduce this problem
  • reduce number of series
• every time you restart the collector, the length can grow, if you restart collector, the length will become 20, restart collector again, 30.
• the collector never reset the points for each series
• the serializer has problem, it is not reset? Yes
  • but the server does not report any error?

Conclusion

• the serializer is not reset after each send, and server drop the invalid part silently when parsing JSON

[at15]

[{"name":"mem.total","tags":{"host":"at15-PC4073"},"points":[[1494832196000,32858548],[1494832197000,32858548],[1494832198000,32858548],[1494832199000,32858548],[1494832200000,32858548],[1494832201000,32858548],[1494832202000,32858548],[1494832203000,32858548],[1494832204000,32858548],[1494832205000,32858548]]},{"name":"mem.free","tags":{"host":"at15-PC4073"},"points":[[1494832196000,20316588],[1494832197000,20317844],[1494832198000,20344596],[1494832199000,20345128],[1494832200000,20339624],[1494832201000,20338972],[1494832202000,20338108],[1494832203000,20338100],[1494832204000,20338960],[1494832205000,20338804]]}]

[{"name":"mem.total","tags":{"host":"at15-PC4073"},"points":[[1494832196000,32858548],[1494832197000,32858548],[1494832198000,32858548],[1494832199000,32858548],[1494832200000,32858548],[1494832201000,32858548],[1494832202000,32858548],[1494832203000,32858548],[1494832204000,32858548],[1494832205000,32858548]]},{"name":"mem.free","tags":{"host":"at15-PC4073"},"points":[[1494832196000,20316588],[1494832197000,20317844],[1494832198000,20344596],[1494832199000,20345128],[1494832200000,20339624],[1494832201000,20338972],[1494832202000,20338108],[1494832203000,20338100],[1494832204000,20338960],[1494832205000,20338804]]}][{"name":"mem.total","tags":{"host":"at15-PC4073"},"points":[[1494832206000,32858548],[1494832207000,32858548],[1494832208000,32858548],[1494832209000,32858548],[1494832210000,32858548],[1494832211000,32858548],[1494832212000,32858548],[1494832213000,32858548],[1494832214000,32858548],[1494832215000,32858548],[1494832216000,32858548]]},{"name":"mem.free","tags":{"host":"at15-PC4073"},"points":[[1494832206000,20338488],[1494832207000,20338372],[1494832208000,20337504],[1494832209000,20337380],[1494832210000,20337248],[1494832211000,20338064],[1494832212000,20337968],[1494832213000,20336976],[1494832214000,20336680],[1494832215000,20336580],[1494832216000,20336208]]}]