This may be your problem: https://issues.apache.org/jira/browse/CASSANDRA-1358
The message deserializer executor is being created with a core pool size of 1. Since it uses a queue with unbounded capacity new requests are always queued and the thread pool never grows. So the message deserializer becomes a single-threaded bottleneck through which all traffic must pass. So your 16 cores are reduced to one core for handling all inter-node communication (and any intra-node communication that's being passed through the messaging service). Mike On Tue, Aug 3, 2010 at 10:02 PM, Dathan Pattishall <datha...@gmail.com>wrote: > The output of htop shows threads as procs with a breakdown of how much cpu > /etc per thread (in ncurses color!). All of these Java "procs" are just Java > threads of only 1 instance of Cassandra per Server. > > > On Sat, Jul 31, 2010 at 3:45 PM, Benjamin Black <b...@b3k.us> wrote: > >> Sorry, I just noticed: are you running 14 instances of Cassandra on a >> single physical machine or are all those java processes something >> else? >> >> On Mon, Jul 26, 2010 at 12:22 PM, Dathan Pattishall <datha...@gmail.com> >> wrote: >> > I have 4 nodes on enterprise type hardware (Lots of Ram 12GB, 16 i7 >> cores, >> > RAID Disks). >> > >> > ~# /opt/cassandra/bin/nodetool --host=localhost --port=8181 tpstats >> > Pool Name Active Pending Completed >> > STREAM-STAGE 0 0 0 >> > RESPONSE-STAGE 0 0 516280 >> > ROW-READ-STAGE 8 4096 1164326 >> > LB-OPERATIONS 0 0 0 >> > MESSAGE-DESERIALIZER-POOL 1 682008 1818682 >> > GMFD 0 0 6467 >> > LB-TARGET 0 0 0 >> > CONSISTENCY-MANAGER 0 0 661477 >> > ROW-MUTATION-STAGE 0 0 998780 >> > MESSAGE-STREAMING-POOL 0 0 0 >> > LOAD-BALANCER-STAGE 0 0 0 >> > FLUSH-SORTER-POOL 0 0 0 >> > MEMTABLE-POST-FLUSHER 0 0 4 >> > FLUSH-WRITER-POOL 0 0 4 >> > AE-SERVICE-STAGE 0 0 0 >> > HINTED-HANDOFF-POOL 0 0 3 >> > >> > EQX r...@cass04:~# vmstat -n 1 >> > >> > procs -----------memory---------- ---swap-- -----io---- --system-- >> > -----cpu------ >> > r b swpd free buff cache si so bi bo in cs us sy >> id >> > wa st >> > 6 10 7096 121816 16244 10375492 0 0 1 3 0 0 5 >> 1 >> > 94 0 0 >> > 2 10 7096 116484 16248 10381144 0 0 5636 4 21210 9820 2 >> 1 >> > 79 18 0 >> > 1 9 7096 108920 16248 10387592 0 0 6216 0 21439 9878 2 >> 1 >> > 81 16 0 >> > 0 9 7096 129108 16248 10364852 0 0 6024 0 23280 8753 2 >> 1 >> > 80 17 0 >> > 2 9 7096 122460 16248 10370908 0 0 6072 0 20835 9461 2 >> 1 >> > 83 14 0 >> > 2 8 7096 115740 16260 10375752 0 0 5168 292 21049 9511 3 >> 1 >> > 77 20 0 >> > 1 10 7096 108424 16260 10382300 0 0 6244 0 21483 8981 2 >> 1 >> > 75 22 0 >> > 3 8 7096 125028 16260 10364104 0 0 5584 0 21238 9436 2 >> 1 >> > 81 16 0 >> > 3 9 7096 117928 16260 10370064 0 0 5988 0 21505 10225 >> 2 1 >> > 77 19 0 >> > 1 8 7096 109544 16260 10376640 0 0 6340 28 20840 8602 2 >> 1 >> > 80 18 0 >> > 0 9 7096 127028 16240 10357652 0 0 5984 0 20853 9158 2 >> 1 >> > 79 18 0 >> > 9 0 7096 121472 16240 10363492 0 0 5716 0 20520 8489 1 >> 1 >> > 82 16 0 >> > 3 9 7096 112668 16240 10369872 0 0 6404 0 21314 9459 2 >> 1 >> > 84 13 0 >> > 1 9 7096 127300 16236 10353440 0 0 5684 0 38914 10068 >> 2 1 >> > 76 21 0 >> > >> > >> > But the 16 cores are hardly utilized. Which indicates to me there is >> some >> > bad thread thrashing, but why? >> > >> > >> > >> > 1 [||||| 8.3%] >> Tasks: >> > 1070 total, 1 running >> > 2 [ 0.0%] Load >> > average: 8.34 9.05 8.82 >> > 3 [ 0.0%] >> Uptime: >> > 192 days(!), 15:29:52 >> > 4 [||||||||||| 17.9%] >> > 5 [||||| 5.7%] >> > 6 [|| 1.3%] >> > 7 [|| 2.6%] >> > 8 [| 0.6%] >> > 9 [| 0.6%] >> > 10 [|| 1.9%] >> > 11 [|| 1.9%] >> > 12 [|| 1.9%] >> > 13 [|| 1.3%] >> > 14 [| 0.6%] >> > 15 [|| 1.3%] >> > 16 [| 0.6%] >> > Mem[||||||||||||||||||||||||||||||||||||||||||||1791/12028MB] >> > Swp[| 6/1983MB] >> > >> > PID USER PRI NI VIRT RES SHR S CPU% MEM% TIME+ Command >> > 30269 root 40 0 14100 2116 900 R 4.0 0.0 0:00.49 htop >> > 24878 root 40 0 20.6G 8345M 6883M D 3.0 69.4 1:23.03 >> > /opt/java/bin/java -ea -Xms1G -Xmx7G -XX:+UseParNewGC -XX:+UseConcMark >> > 24879 root 40 0 20.6G 8345M 6883M D 3.0 69.4 1:22.93 >> > /opt/java/bin/java -ea -Xms1G -Xmx7G -XX:+UseParNewGC -XX:+UseConcMark >> > 24874 root 40 0 20.6G 8345M 6883M D 2.0 69.4 1:22.73 >> > /opt/java/bin/java -ea -Xms1G -Xmx7G -XX:+UseParNewGC -XX:+UseConcMark >> > 24880 root 40 0 20.6G 8345M 6883M D 2.0 69.4 1:22.93 >> > /opt/java/bin/java -ea -Xms1G -Xmx7G -XX:+UseParNewGC -XX:+UseConcMark >> > 24875 root 40 0 20.6G 8345M 6883M D 2.0 69.4 1:23.17 >> > /opt/java/bin/java -ea -Xms1G -Xmx7G -XX:+UseParNewGC -XX:+UseConcMark >> > 24658 root 40 0 20.6G 8345M 6883M D 2.0 69.4 1:23.06 >> > /opt/java/bin/java -ea -Xms1G -Xmx7G -XX:+UseParNewGC -XX:+UseConcMark >> > 24877 root 40 0 20.6G 8345M 6883M S 2.0 69.4 1:23.43 >> > /opt/java/bin/java -ea -Xms1G -Xmx7G -XX:+UseParNewGC -XX:+UseConcMark >> > 24873 root 40 0 20.6G 8345M 6883M D 1.0 69.4 1:23.65 >> > /opt/java/bin/java -ea -Xms1G -Xmx7G -XX:+UseParNewGC -XX:+UseConcMark >> > 24876 root 40 0 20.6G 8345M 6883M S 1.0 69.4 1:23.62 >> > /opt/java/bin/java -ea -Xms1G -Xmx7G -XX:+UseParNewGC -XX:+UseConcMark >> > 24942 root 40 0 20.6G 8345M 6883M S 1.0 69.4 0:23.50 >> > /opt/java/bin/java -ea -Xms1G -Xmx7G -XX:+UseParNewGC -XX:+UseConcMark >> > 24943 root 40 0 20.6G 8345M 6883M S 0.0 69.4 0:29.53 >> > /opt/java/bin/java -ea -Xms1G -Xmx7G -XX:+UseParNewGC -XX:+UseConcMark >> > 24933 root 40 0 20.6G 8345M 6883M S 0.0 69.4 0:22.57 >> > /opt/java/bin/java -ea -Xms1G -Xmx7G -XX:+UseParNewGC -XX:+UseConcMark >> > 24939 root 40 0 20.6G 8345M 6883M S 0.0 69.4 0:12.73 >> > /opt/java/bin/java -ea -Xms1G -Xmx7G -XX:+UseParNewGC -XX:+UseConcMark >> > 25280 root 40 0 20.6G 8345M 6883M S 0.0 69.4 0:00.10 >> > /opt/java/bin/java -ea -Xms1G -Xmx7G -XX:+UseParNewGC -XX:+UseConcMark >> > >> > >
