3:14 p.m.
[
https://issues.redhat.com/browse/ISPN-11679?page=com.atlassian.jira.plugi...
]
Masafumi Miura commented on ISPN-11679:
---------------------------------------
Here is the example result of the unit test with 22 nodes:
{code}
[INFO] -------------------------------------------------------
[INFO] T E S T S
[INFO] -------------------------------------------------------
[INFO] Running
org.infinispan.distribution.ch.SyncConsistentHashFactoryKeyDistributionTest
[OK: 0, KO: 0, SKIP: 0] Test starting:
org.infinispan.distribution.ch.SyncConsistentHashFactoryKeyDistributionTest.testRebalanceDistribution
Distribution for 22 nodes (relative to the average)
===
Segments = 200 220 400 440 600 660 720
800 880 1000 1100
Any owner: % < 0.60 = 1.46% 0.00% 0.12% 0.00% 0.03% 0.02% 0.01%
0.00% 0.00% 0.00% 0.00%
Any owner: % < 0.70 = 4.54% 0.00% 0.91% 0.00% 0.33% 0.13% 0.12%
0.07% 0.07% 0.03% 0.01%
Any owner: % < 0.80 = 11.69% 0.02% 3.12% 0.00% 2.85% 1.73% 1.66%
1.19% 0.81% 1.03% 0.70%
Any owner: % < 0.90 = 23.57% 3.80% 11.91% 0.45% 12.28% 10.06% 8.65%
8.26% 6.84% 10.01% 8.64%
Any owner: % > 1.10 = 42.02% 0.72% 7.25% 0.15% 7.82% 0.43% 1.80%
1.55% 0.06% 2.04% 0.17%
Any owner: % > 1.15 = 14.77% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00%
0.00% 0.00% 0.00% 0.00%
Any owner: % > 1.30 = 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00%
0.00% 0.00% 0.00% 0.00%
Any owner: % > 1.50 = 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00%
0.00% 0.00% 0.00% 0.00%
Any owner: 99.90% percentile = 1.167 1.150 1.139 1.125 1.130 1.117 1.123
1.125 1.100 1.122 1.110
Any owner: max = 1.167 1.150 1.139 1.125 1.130 1.117 1.123
1.125 1.113 1.122 1.110
Any owner: min = 0.222 0.800 0.444 0.850 0.500 0.550 0.523
0.639 0.650 0.622 0.700
Primary: % < 0.60 = 1.68% 0.00% 0.10% 0.00% 0.03% 0.02% 0.01%
0.00% 0.00% 0.00% 0.00%
Primary: % < 0.70 = 5.32% 0.00% 0.70% 0.00% 0.23% 0.17% 0.11%
0.10% 0.05% 0.04% 0.01%
Primary: % < 0.80 = 13.24% 0.00% 3.56% 0.00% 2.42% 1.96% 1.02%
1.01% 0.89% 1.20% 0.75%
Primary: % < 0.90 = 26.48% 0.01% 13.25% 0.01% 13.74% 11.12% 5.67%
8.96% 7.39% 9.02% 9.20%
Primary: % > 1.10 = 56.32% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00%
0.00% 0.00% 0.00% 0.00%
Primary: % > 1.15 = 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00%
0.00% 0.00% 0.00% 0.00%
Primary: % > 1.30 = 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00%
0.00% 0.00% 0.00% 0.00%
Primary: % > 1.50 = 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00%
0.00% 0.00% 0.00% 0.00%
Primary: 99.90% percentile = 1.111 1.000 1.056 1.000 1.074 1.033 1.063
1.056 1.025 1.067 1.040
Primary: max = 1.111 1.000 1.056 1.000 1.074 1.033 1.063
1.056 1.025 1.067 1.040
Primary: min = 0.222 1.000 0.444 1.000 0.519 0.567 0.531
0.611 0.675 0.622 0.700
Segments per node - max/min ratio = 5.250 1.438 2.500 1.294 2.222 1.970 2.088
1.717 1.673 1.804 1.549
[OK: 1, KO: 0, SKIP: 0] Test succeeded:
org.infinispan.distribution.ch.SyncConsistentHashFactoryKeyDistributionTest.testRebalanceDistribution
[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 71.962 s - in
org.infinispan.distribution.ch.SyncConsistentHashFactoryKeyDistributionTest
{code}
If the number of the segment is configured as the exact same to "20 * number of
nodes" (= 440 in the above example), the test result looks slightly better than other
cases. Is this an expected result?
Bad uneven segment distributions can happen after the rebalancing
with SyncConsistentHashFactory
------------------------------------------------------------------------------------------------
Key: ISPN-11679
URL: https://issues.redhat.com/browse/ISPN-11679
Project: Infinispan
Issue Type: Bug
Components: Core
Affects Versions: 9.4.19.Final, 10.1.6.Final
Reporter: Masafumi Miura
Priority: Major
Uneven segment distribution can happen after rebalancing with SyncConsistentHashFactory.
Even if a larger number of segments than "20 * number of nodes" is configured,
some nodes have only around 50-60% number of segments than other nodes after the rebalance
in the worst case.
I understand the documentation (like the following) states about the possibility of
slight uneven distribution as a potential drawback of SyncConsistentHashFactory.
[Infinispan 10 configuration
guide|https://infinispan.org/docs/stable/titles/configuring/configuring.h...]
says:
{quote}
This implementation does have some negative points in that the load distribution is
slightly uneven. It also moves more segments than strictly necessary on a join or leave.
{quote}
[JDG 7 Developer
Guide|https://access.redhat.com/documentation/en-us/red_hat_data_grid/7.2...]
says:
{quote}
It has a potential drawback in that it can move a greater number of segments than
necessary during re-balancing. This can be mitigated by using a larger number of
segments.
Another potential drawback is that the segments are not distributed as evenly as
possible, and actually using a very large number of segments can make the distribution of
segments worse.
{quote}
However, only half segments than others is not a slight uneven.
--
This message was sent by Atlassian Jira
(v7.13.8#713008)