startup time, slow "Executable WAR" with JDWP?
Pascal Rigaux
Hi,
I was modifying templates and found a way to keep using embedded tomcat while being able to easily modify the templates (since then I tried using templates outside of classpath) :
gradle unzipWAR && java -cp "build/app:build/app/WEB-INF/classes:build/app/WEB-INF/lib/*" org.springframework.boot.loader.WarLauncher
I wondered why it was much faster to start... So I tested various possibilities.
(NB: I often enable jdwp by default just in case it can be useful to see things with a debugger)
Below are some quite astonishing results...
| elapsed | CPU | |
| WarLauncher on exploded WAR | 18 s | 25 s |
| WarLauncher on exploded WAR + jdwp | 18 s | 26 s |
| java -jar cas.war | 37 s | 47 s |
| java -jar cas.war + jdwp | 96 s | 109 s |
| tomcat (exploded ou war) | 33 s | 43 s |
| tomcat + jdwp | 36 s | 46 s |
| overheads: | ||
| java -jar cas.war | 106 % | 88 % |
| tomcat | 83 % | 72 % |
| jdwp (for WarLauncher on exploded WAR) | 0 % | 4 % |
| jdwp (for java -jar cas.war) | 159 % | 132 % |
| jdwp (for tomcat) | 9 % | 7 % |
tested with
- AdoptOpenJDK 15.0.2+7 (also tested debian openjdk 11.0.6+10-1~bpo9+1 with only minor changes)
- CAS 6.4.2 with various modules
- tomcat 9.0.54
- somewhat old OS : debian 9 on VMware
details:
- WarLauncher on exploded WAR = java -cp "build/app:build/app/WEB-INF/classes:build/app/WEB-INF/lib/*" org.springframework.boot.loader.WarLauncher
- CPU = "TIME" column of ps (ie "accumulated cpu time, user + system")
- elapsed = time it takes to reach CAS "Ready to process requests"
Pascal Rigaux
Hi again :
I just found out that my tests were running with TieredCompilation...
Here are some more test results below.
Conclusions:
=> TieredCompilation is a good CPU win, but often a bad elapsed choice
=> executable war & tomcat >50% elapsed overhead (?!)
=> jdwp is mostly harmless (except for Excutable WAR + JDWP + TieredCompilation)
NB :
- tested on a VM with 8 vCPUs
- tested with the following TieredCompilation options: -XX:+TieredCompilation -XX:TieredStopAtLevel=1
| par défaut | TieredCompilation | TieredCompilation overhead | ||||
| elapsed | CPU | elapsed | CPU | elapsed | CPU | |
| WarLauncher on exploded WAR | 18 s |
| 68 s | 18 s | 25 s | 0 % | -63 % |
| WarLauncher on exploded WAR + jdwp | 18 s |
| 75 s | 18 s | 26 s | 0 % | -65 % | ||
| java -jar cas.war | 28 s | 90 s | 37 s | 47 s | 32 % | -48 % |
| java -jar cas.war + jdwp |
| 31 s | 106 s | 96 s | 109 s | 210 % | 3 % | |
| tomcat (exploded ou war) | 28 s | 91 s | 33 s | 43 s | 18 % | -53 % |
| tomcat + jdwp | 33 s | 109 s | 36 s | 46 s | 9 % | -58 % |
| overheads: | ||||||
| java -jar cas.war | 56 % | 32 % | 106 % | 88 % | ||
| tomcat | 56 % | 34 % | 83 % | 72 % | ||
| jdwp (for WarLauncher on exploded WAR) | 0 % |
| 10 % | 0 % | 4 % | ||
| jdwp (for java -jar cas.war) |
| 11 % | 18 % | 159 % | 132 % | |||
| jdwp (for tomcat) | 18 % | 20 % | 9 % | 7 % |
Pascal Rigaux <Pascal...@univ-paris1.fr> a écrit :