[FOP-2525] [PATCH] Excessive memory usage when using truetype collection (.ttc)

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 2.0
• Environment: At least Mac and Linux, both Oracle VM and OpenJDK
• Assignee: Simon Steiner
• Reporter: Jeremy Smith
• Created: 14/Sep/15 16:56
• Updated: 28/Jan/17 17:55
• Resolved: 06/Oct/16 08:57

Description

When a TrueType Collection file is used to specify custom fonts, and a long-running FopFactory is used to create FOP instances to process many FO input documents, millions of org.apache.fop.complexscripts.fonts.GlyphPositioningTable$PairValues and org.apache.fop.complexscripts.fonts.GlyphPositioningTable$Values instances get created which are never collected. Thus the heap continues to grow, leading to eventual GC thrashing or crash.

When the same fonts are used, but extracted from the TTC file, the issue does not occur, and the instances of those classes are collected normally.

The issue can be seen by repeatedly processing a document with a config.xml which specifies fonts inside of a Truetype Collection file. Attaching VisualVM to such a process will show continuous heap growth and millions of aforementioned instances whose numbers never decrease.