Getting Segfault writing feather about feather

[hadley]

Can you please provide a reproducible example, preferably without any data.table? (to ensure that isn't the root cause)

[shapenaji]

I'll see what I can do, there are a lot of random characters in this df, (and for proprietary reasons, I unfortunately can't include it, I'll see if I can find a subset where it's the case), maybe I can randomly sample the characters in my fields...

[shapenaji]

Reproduced it, it's coming from fread, read.csv does not trigger it, but I can't seem to generate it with random data. Trying to figure out which one it is

[hadley]

Try narrowing down to a specific column - the most likely culprit is likely to be a character column, given that read.csv() doesn't illustrate the problem.

[shapenaji]

Sorry for the delay: Got it, seems to have to do with empty characters.

here we go:

library(data.table)
library(feather)
write.csv(data.table(x = rep('',5)),'test.csv')
z <- fread('test.csv', data.table = FALSE)
write_feather(z,  'testfeath')

[hadley]

Doesn't seem to be anything to do with data.table:

write_feather(data.frame(x = rep('',5)), "test.feather")

@wesm Am I doing something wrong here? Here's the backtrace:

* thread #1: tid = 0x177ea17, 0x000000010a8f9e07 feather.so`chrToPrimitiveArray(SEXPREC*) [inlined] feather::Buffer::data(this=<unavailable>) const + 7 at buffer.h:51, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x10)
  * frame #0: 0x000000010a8f9e07 feather.so`chrToPrimitiveArray(SEXPREC*) [inlined] feather::Buffer::data(this=<unavailable>) const + 7 at buffer.h:51
    frame #1: 0x000000010a8f9e00 feather.so`chrToPrimitiveArray(x=0x00007fff5fbfcdc0) + 704 at feather-write.cpp:221
    frame #2: 0x000000010a8fa5b7 feather.so`addCategoryColumn(table=0x00007fff5fbfcef8, name="x", x=0x000000010588dd28) + 119 at feather-write.cpp:265
    frame #3: 0x000000010a8fabfb feather.so`addColumn(table=0x00007fff5fbfcef8, name="x", x=0x000000010588dd28) + 59 at feather-write.cpp:314
    frame #4: 0x000000010a8faeda feather.so`writeFeather(df=Rcpp::DataFrame @ 0x00007fff5fbfcfa0, path=<unavailable>) + 538 at feather-write.cpp:340

I think the problem is that because there are only empty strings, the size_ of the BufferBuilder is 0 and data_ is a nullptr.

[wesm]

I'm able to get a core dump in Python, too. Patch incoming

[wesm]

Can you confirm #86 fixes the bug in R, too?

[shapenaji]

Works for me! Thank you!