Our service runs on AWS on m5.12xlarge nodes (48 cores, 192 G RAM) on Ubuntu 16.04. We use Java 8. For our service we allocate about 150G as max heap size. We have no swap on the node. The nature of our service is that it allocates a lot of large short-lived objects. Apart from … Read more
One of our java application is taking big pause while doing GC, it seems because of “ParNew (promotion failed)” it takes time. Java version: $ java -version java version “1.6.0_21” Java(TM) SE Runtime Environment (build 1.6.0_21-b06) Java HotSpot(TM) 64-Bit Server VM (build 17.0-b16, mixed mode) GC setting: JAVA_OPTS=”$JAVA_OPTS -XX:+PrintGCApplicationConcurrentTime -XX:+PrintGCApplicationStoppedTime -XX:+PrintGCDateStamps -XX:+PrintGCDetails -XX:+PrintGCTimeStamps -XX:+PrintTenuringDistribution -Dsun.rmi.dgc.client.gcInterval=86400000 … Read more
The SSD controller triggers the garbage collection routines on a specific ship or block when a certain threshold of either invalid pages or written pages is met, based on the GC policy (my guess is that most SSDs use the greedy policy). I am trying to measure the impact of some workloads on a specific … Read more
Solid State Drives (SSD) have a garbage collection functionality which makes space from deleted files available. It is triggered automatically by the drive via a TRIM command sent by the OS Is there a way to put an SSD in a state where the automatic garbage collection does not occur? Having forensics data collection in … Read more
Does anyone know if the PrintGCDetails affects java performance much? I’ve been monitoring our java garbage collecting on a staging server with the same setup as the production server. I assumed it was safe to say that I shouldn’t have this enabled on production but I don’t know if there’s really any affect on performance. … Read more
I’ve been trying to track down the cause of intermittent slowdowns of our Tomcat server. We get the slowdowns several times a week, where Tomcat will stop responding or take several minutes to process requests, and the cpu loads on the (Linux) box, as shown by uptime, spike from typically around 1-2 to over 30. … Read more
Debian and derivatives (Ubuntu) don’t use the php session garbage collector session.gc_probability = 0 instead they use a cron /etc/cron.d/php5 09,39 * * * * root [ -x /usr/lib/php5/maxlifetime ] && [ -d /var/lib/php5 ] && find /var/lib/php5/ -depth -mindepth 1 -maxdepth 1 -type f -cmin +$(/usr/lib/php5/maxlifetime) ! -execdir fuser -s {} 2>/dev/null \; -delete … Read more
