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https://issues.apache.org/jira/browse/DERBY-6841?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15006017#comment-15006017
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Bryan Pendleton commented on DERBY-6841:
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I recall that System.currentTimeMillis can be a problematic method for timing,
because its precision is not so good. So I speculatively changed your program
to replace System.currentTimeMillis with System.nanoTime in the timestamp()
method and re-ran my 6 tests.
Here are the results. First 3x with trunk:
[bpendleton@Fedora22 DERBY-6841]$ java -cp .:$CLASSPATH DERBY_6841
Booted database 0 average over 100 times = 5.310609034E7
Shutdown database 0 average over 100 times = 2.473811778E7
Shutdown engine average over 1 times = 3935768.0
[bpendleton@Fedora22 DERBY-6841]$ java -cp .:$CLASSPATH DERBY_6841
Booted database 0 average over 100 times = 3.881974931E7
Shutdown database 0 average over 100 times = 2.397720971E7
Shutdown engine average over 1 times = 4498394.0
[bpendleton@Fedora22 DERBY-6841]$ java -cp .:$CLASSPATH DERBY_6841
Booted database 0 average over 100 times = 3.701070247E7
Shutdown database 0 average over 100 times = 2.357004649E7
Shutdown engine average over 1 times = 5198444.0
[bpendleton@Fedora22 DERBY-6841]$ java -cp .:$CLASSPATH DERBY_6841
Booted database 0 average over 100 times = 3.708846844E7
Shutdown database 0 average over 100 times = 2.455780294E7
Shutdown engine average over 1 times = 5192656.0
Then 3x with the 10.11 lib distribution:
[bpendleton@Fedora22 DERBY-6841]$ java -cp
.:db-derby-10.11.1.1-lib/lib/derbyrun.jar DERBY_6841
Booted database 0 average over 100 times = 4.835111398E7
Shutdown database 0 average over 100 times = 2.161155859E7
Shutdown engine average over 1 times = 3523968.0
[bpendleton@Fedora22 DERBY-6841]$ java -cp
.:db-derby-10.11.1.1-lib/lib/derbyrun.jar DERBY_6841
Booted database 0 average over 100 times = 3.288749179E7
Shutdown database 0 average over 100 times = 2.109016233E7
Shutdown engine average over 1 times = 5468161.0
[bpendleton@Fedora22 DERBY-6841]$ java -cp
.:db-derby-10.11.1.1-lib/lib/derbyrun.jar DERBY_6841
Booted database 0 average over 100 times = 3.119072684E7
Shutdown database 0 average over 100 times = 2.203508767E7
Shutdown engine average over 1 times = 4724186.0
> Derby v10.12.1.1 is horribly slow compared to v10.11.1.1 in embedded mode
> -------------------------------------------------------------------------
>
> Key: DERBY-6841
> URL: https://issues.apache.org/jira/browse/DERBY-6841
> Project: Derby
> Issue Type: Bug
> Components: JDBC, SQL
> Affects Versions: 10.12.1.1
> Environment: OS: Windows, OS X, Linux
> CPU: Quad-Core Intel i5
> App: Swing, multi-threaded
> Reporter: Xavion
> Fix For: 10.11.1.1
>
> Attachments: DERBY_6841.java
>
>
> It takes much longer to open, read, and close embedded databases using
> v10.12.1.1 than it did with v10.11.1.1. What ever changes you guys made over
> the last year and a bit have definitely been for the worse.
> Below are the results of the repetition tests I've just run on the same
> computer with the same databases. Let me know if you need to know about the
> sizes of the databases and/or the file type they contain.
> Connecting with v10.11.1.1:
> Database opened in 0.82 seconds.
> Database opened in 0.77 seconds.
> Database opened in 0.88 seconds.
> Database opened in 0.77 seconds.
> Database opened in 0.77 seconds.
> Database opened in 0.96 seconds.
> Database opened in 0.74 seconds.
> Connecting with v10.12.1.1:
> Database opened in 1.98 seconds.
> Database opened in 2.07 seconds.
> Database opened in 1.97 seconds.
> Database opened in 2.01 seconds.
> Database opened in 2.01 seconds.
> Database opened in 2.00 seconds.
> Database opened in 2.03 seconds.
> Reading with v10.11.1.1:
> Database processed in 6.17 seconds.
> Database processed in 4.00 seconds.
> Database processed in 3.67 seconds.
> Database processed in 3.66 seconds.
> Database processed in 3.78 seconds.
> Database processed in 3.69 seconds.
> Database processed in 3.74 seconds.
> Reading with v10.12.1.1:
> Database processed in 7.29 seconds.
> Database processed in 4.54 seconds.
> Database processed in 4.88 seconds.
> Database processed in 4.65 seconds.
> Database processed in 4.34 seconds.
> Database processed in 4.35 seconds.
> Database processed in 4.50 seconds.
> Disconnecting with v10.11.1.1:
> Database closed in 0.11 seconds.
> Database closed in 0.13 seconds.
> Database closed in 0.15 seconds.
> Database closed in 0.14 seconds.
> Database closed in 0.10 seconds.
> Database closed in 0.13 seconds.
> Database closed in 0.14 seconds.
> Disconnecting with v10.12.1.1:
> Database closed in 0.74 seconds.
> Database closed in 0.87 seconds.
> Database closed in 0.76 seconds.
> Database closed in 0.87 seconds.
> Database closed in 0.85 seconds.
> Database closed in 0.69 seconds.
> Database closed in 0.84 seconds.
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