My Java application does quite a lot of synchronization with databases. Each such single event is logged, e.g.
logger.info("Starting synchronization...");
synchronizeWithDatabase();
logger.info("Synchronization has ended.");
This clutters logs quite a lot. Would it be possible to log a summary every hour (e.g. "there were 60 successful synchronization events from 12:00:00 to 13:00:00") and only log errors per occurrence? I'm using slf4j Logger
The straightforward way is to write code to do what you want. Write a wrapper class that, for each "event", tracks the last time you actually logged the event, and the number of times it has occurred.
Then on a call for which the time-since-logged exceeds an hour, actually write the log message, and reset the counter.
Here's a sketch off the top of my head. Hasn't been near a compiler. Not intended as a fully-baked solution.
class QuenchData {
private static final long delta = 1000 * 60 * 60; // 1 hr
private long lastLogTime;
private int count;
void log(String message, Logger logger) {
long now = System.getTimeInMillis();
if (now < lastLogTime || now-lastLogTime >= delta) {
String andAlso = String.format(" [occurred %d times]", count);
logger.log(message + andAlso);
lastLogTime = now;
count = 0;
} else
count++;
}
}
}
class QuenchedLogger {
private Logger logger = new Logger(...whatever...);
private Map<String, QuenchData> history = new HashMap<>();
:
synchronized void log(String message) {
QuenchData qd = history.get(message);
if (qd == null)
history.put(message, (qd = new QuenchData()));
qd.log(message, logger);
}
}