Issue2886

classification

Milestone:
Title:	doing relative imports in a loop causes bad performance due to 2472
Type:	behaviour	Severity:	major
Components:	Core	Versions:	Jython 2.7.2

process

Dependencies:	Superseder:
Status:	open	Resolution:
Assigned To:	Nosy List:	hansiang93
Priority:	Keywords:

Created on 2020年05月08日.23:03:32 by hansiang93, last changed 2020年05月08日.23:05:23 by hansiang93.

Messages
msg13048 (view)	Author: han (hansiang93)	Date: 2020年05月08日.23:04:14
the issue https://bugs.jython.org/issue2472 and its subsequent resolution bc317e2 causes a side effect where jython will attempt to find a relative import again and again despite having done so in the past. This violates expected python 2.7 relative import optimisation that places a None whenever an import is not found as opposed to null. Consider the case of a local import being done on a loop without the use of absolute imports, we will attempt to generate all java classes, org.python.core.JavaImportHelper.tryAddPackage(), org.python.core.JavaImportHelper.buildLoadedPackages(), and java.lang.Package.getPackages() which add up to tons of CPU time usage.

Messages

msg13048 (view)

Author: han (hansiang93)

Date: 2020年05月08日.23:04:14

the issue https://bugs.jython.org/issue2472 and its subsequent resolution bc317e2 causes a side effect where jython will attempt to find a relative import again and again despite having done so in the past.
This violates expected python 2.7 relative import optimisation that places a None whenever an import is not found as opposed to null.
Consider the case of a local import being done on a loop without the use of absolute imports, we will attempt to generate all java classes, org.python.core.JavaImportHelper.tryAddPackage(), org.python.core.JavaImportHelper.buildLoadedPackages(), and java.lang.Package.getPackages() which add up to tons of CPU time usage.

History
Date	User	Action	Args
2020年05月08日 23:05:23	hansiang93	set	type: crash -> behaviour components: + Core
2020年05月08日 23:04:14	hansiang93	set	messages: + msg13048 title: -Qnew results in jython failing -> doing relative imports in a loop causes bad performance due to 2472
2020年05月08日 23:03:32	hansiang93	create