[gpfsug-discuss] Meaning of new fields in Watchfolder output
Hannappel, Juergen
juergen.hannappel at desy.de
Mon Mar 21 12:37:39 GMT 2022
Hi,
for a test I read from a file with dd:
dd if=someFile bs=64k of=/dev/null
This will do 2 reads with 64k bytes, one read with 24053 and one final read with 0 bytes.
I now check the WF json output, looking for the new ReadOffset and bytesRead fields I get:
kafkacat -b my-broker -t test1-watch | while read mist; do echo $mist | python -m json.tool | grep -i read ; done
"bytesRead": "0",
"minReadOffset": "9223372036854775807",
"maxReadOffset": "0",
That is the open()...
"bytesRead": "65536",
"minReadOffset": "0",
"maxReadOffset": "65535",
That is the first read()....
"bytesRead": "131072",
"minReadOffset": "0",
"maxReadOffset": "131071",
WHo reads 2x64k bytes from the beginning? Is the the accumulated read data?
"bytesRead": "155125",
"minReadOffset": "0",
"maxReadOffset": "155124",
And again, now it looks as if in one event the entire file is read?
The documentation (https://www.ibm.com/docs/en/spectrum-scale/5.1.3?topic=folder-json-attributes-in-clustered-watch)
doesn't explain this....
--
Dr. Jürgen Hannappel DESY/IT Tel. : +49 40 8998-4616
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