Where to print logs
Use INFO logs to reply upstream or downstream caller
INFOlogs represent main cases.- If more
INFOlogs printed, the volume of logs will be increased rapidly. - But in the entrance and exit of component,
INFOlogs should be required to reply the question from upstream or downstream caller, for the running status.
Component entrance log
LOGGER.info("Kafka-OnMessage isOracleBased={}, subscriptionID={}, " +
", objectType={} " +
", key={}, csn={}, consumer-partition={}, consumer-offset={} " +
", topic-endOffset={} " + " onMsgTime={}. decompressedTime={}" ,
isOracleBased,
subscriptionId,
objType,
consumerRecord.key(),
msgCSN,
consumerRecord.partition(),
consumerRecord.offset(),
endOffset,
startTime,
(System.currentTimeMillis() - startTime));
Component exit log
LOGGER.info("DONE-Process-CSN =" + msgCSN + ", subDN=" + getSubscriptionDN() + ", duration=" + duration +
", isOracle=" + isOracleBased + ", partition=" + consumerRecord.partition() +
", comittedOffset=" + consumerRecord.offset() +
", partitionEndOffset=" + endOffset);
Use WARN logs to handle normal exception cases
- The opposite of main cases are exception cases. E.g, in Push service, message consumed from Kafka, then sent out, which called main case, the rest of cases are all exception cases.
- The exception cases occurred, but
nothing can be done, which callednormal exceptioncases,WARNcan be used. E.g, message is filtered out for changed attributes not interested.
LOGGER.warn("Oracle changedAttrs not interested, msgCSN: {}, changedAttrs: {}", msgCSN, changedAttrList);
Use ERROR logs to handle abnormal exception cases
- The exception cases occurred, but
something can be done to fix it, which calledabnormal exceptioncases,ERRORcan be used. E.g, Kafka connection failed.
LOGGER.error("IDFY_KAFKA_SSL_ERROR : SSL Exception on delivering to '{}' Sub= {} ,"+ "CSN= {} '{}' - {}",
endpoint,
subscriptionIdentifier,
csn,
LogUtils.string2LogString(message), t.getMessage());
How to print logs
Must print business words
Bad smell
private void set(String key, byte[] value, long expiryMills) {
if (proxy != null) {
try {
proxy.set(key, value, expiryMills);
} catch (RedisException e) {
LOGGER.error(e.getMessage(), e);
}
}
}
Better to print unique words
Good smell
LOGGER.error("Cannot generate pusher for {} - {}", objectType, subscriptionDN);
Bad smell
LOGGER.error("missing objectType in subscriptionBody");