| Summary: | Unzip performance regression on Windows due to BZ 62502 | ||
|---|---|---|---|
| Product: | Ant | Reporter: | Falko Modler <f.modler> |
| Component: | Core tasks | Assignee: | Ant Notifications List <notifications> |
| Status: | NEW --- | ||
| Severity: | normal | CC: | Mriza2467 |
| Priority: | P2 | ||
| Version: | 1.9.13 | ||
| Target Milestone: | --- | ||
| Hardware: | PC | ||
| OS: | All | ||
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Description
Falko Modler
2018-12-09 22:45:05 UTC
Hello Falko, Is this target using "unzip" in just a basic manner or is there anything more to it? If possible, can you attach that target. >> I guess the problem is the use of File.getCanoniocalPath() (twice for each file being extracted) Looking at the code in question (the one which calls the FileUtils.isLeadingPath()), the "dir" will always be same destination directory. So even if we end up calling getCanonicalPath twice, I would expect the JRE implementation to return a cached value (as far as I remember, 1.8.x latest version of Java still uses canonical path cache). So I think, it shouldn't be that expensive (relatively). However, I'm not stating that this isn't the cause and you probably are right that this change ended up being expensive. >> Unfortunately I am not allowed to share the JBoss EAP 6.4 zipfile I was testing with (a RedHat subscription is required). The file is around 300 MB and cotains 1340 directories and 1517 files. Can you post the timings though, with 1.9.12 and 1.9.13? That will give us some idea on what kind of performance regression we are seeing. In the meantime, I'll see if I can reproduce this on a *nix with a similar large file. FWIW - I gave it a try with the community version of JBoss EAP, the WildFly zip file (which is around 172MB and somewhat similar to the EAP zip contents) but I couldn't notice any difference is timing performance between latest and older versions of Ant. I am on a *nix system. It would be good to have a build file or other additional data to reproduce this. >> Is this target using "unzip" in just a basic manner or is there anything more to it? It's really just basic unzip. >> I would expect the JRE implementation to return a cached value Ok, maybe - I don't know. I just had a quick look at the code and did some research on the method and found various blog entries etc. that contained a warning that this method should be used sparingly. If there is some caching, it must reside in native code. Another question is: Does it cache sub-paths? Each file from a zip (normally) has an unique path string... >> Can you post the timings though, with 1.9.12 and 1.9.13? I ran some tests and while there *is* a noticeable/distinct delay, it is *not* "threefold" as I stated initially. I am not sure where/how I saw this massive delay. 1.9.12 allowFilesToEscapeDest=false: ~8s 1.9.12 allowFilesToEscapeDest=true : ~8s 1.9.13 allowFilesToEscapeDest=false: ~10s 1.9.13 allowFilesToEscapeDest=true : ~8s In the end this leaves us with a ~25% penalty. PS: As I don't use standalone Ant, the tests were conducted with: - maven-anrtun-plugin (with updated ant dependency) - Maven 3.3.9 - Java version: 1.8.0_192, vendor: Oracle Corporation - Default locale: de_DE, platform encoding: Cp1252 - OS name: "windows 10", version: "10.0", arch: "amd64", family: "dos" Hardware: - Thinkpad P51 - Intel Core i7-7820HQ - 64GB RAM - Bitlocker-enabled NTFS partition on a Samsung SSD 960 Pro 1TB - Virus Scanner (McAfee) is *not* active for the involved files/folders |