1586649 - [BinAST] Reduce the amount of allocation/free in context parser

Status: RESOLVED INCOMPLETE

(Core :: JavaScript Engine, task, P3)

Description

[Tooru Fujisawa [:arai]]

While reading BinAST context format, allocation/free frequently happens because of Vector and HashTable used while reading header,
and that results in locking Mutex frequently inside mozjemalloc.

We should try reducing the call for malloc/free, maybe by using different pre-allocated size, or different allocator/AllocPolicy, or adding yet another allocator/AllocPolicy with temporary space?

Comment 1

[David Teller [:Yoric] - still alive but not very active]

For what it's worth, normally, everything is Vector now.

I have tried to increase pre-allocated size, but doing it as a simple hack killed the stack :/

Comment 2

[Tooru Fujisawa [:arai]]

Given the following:

• we know the required size at the allocation
• no reallocation happens
• many things have same life time

adding dedicated AllocPolicy with temporary space might work.

Also, about pre-alocated size, given allocating SingleLookupHuffmanTable.{values,saturated} with 1 happens frequently, we could add non-Vector based variant with fixed size array would work nicely.

Comment 3

[Matthew Gaudet (he/him) [:mgaudet]]

Resolving BinAST bugs as Incomplete.