Trivial Description
Someone decided to use a large number for their myid file. This cause session ids to go negative, and our software (Apache Accumulo) did not handle this very well. While diagnosing the problem, I noticed this in SessionImpl:
public static long initializeNextSession(long id) {
long nextSid = 0;
nextSid = (System.currentTimeMillis() << 24) >> 8;
nextSid = nextSid | (id <<56);
return nextSid;
}
When the 40th bit in System.currentTimeMillis() is a one, sign extension will fill the upper 8 bytes of nextSid, and id will not make the session id unique. I recommend changing the right shift to the logical shift:
public static long initializeNextSession(long id) {
long nextSid = 0;
nextSid = (System.currentTimeMillis() << 24) >>> 8;
nextSid = nextSid | (id <<56);
return nextSid;
}
But, we have until the year 2022 before we have to worry about it.