Skip to content

fread fails when max_nrows argument is too small #2243

Description

@st-pasha

Example:

> fread("~/github/h2oai-benchmarks/Data/Homesite/train.csv", nrows=10)

 *** caught segfault ***
address 0x2596, cause 'memory not mapped'
R(60974,0x700000804000) malloc: *** error for object 0x7f97e8d9c0b8: incorrect checksum for freed object - object was probably modified after being freed.
*** set a breakpoint in malloc_error_break to debug
Abort trap: 6

Reason: around line 1794 we compute size_t initialBuffRows = allocnrow / (size_t)nJumps;. Here allocnrow is small (set by the user), while nJumps is large (determined by the file size). As a result, 0 rows are allocated for the buffers, and subsequently any attempt to write into them causes a segfault.

Activity

  1. added this to the milestone on Jul 4, 2017
  2. self-assigned this
    on Jul 4, 2017
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Metadata

Metadata

Assignees

Type

No type

Projects

No projects

    Milestone

    Relationships

    None yet

    Development

    No branches or pull requests

    Issue actions