Why is ImageMagick within node.js crashing? - node.js

Question

I'm using node.js, node-vips and libvips compiled with ImageMagick to convert and resize images. I'm getting segmentation faults and failed assertions when I try and resize more than a couple of images.
I've had so many different crashes I'm not sure where to begin. I started off with libvips 7.26.8, I've also tried 7.30.7. This is with node v0.8.17 compiled from source, on a fairly standard, clean ubuntu box.
#0 0x0000158ac3765c59 in ?? ()
Cannot access memory at address 0x7fffa837ec90
#0 0x0000000000000000 in ?? ()
#1 0x0000000000000000 in ?? ()
node: ../deps/uv/src/unix/stream.c:729: uv__stream_io: Assertion `!!(events & EV_READ) ^ !!(events & EV_WRITE)' failed.
Aborted (core dumped)
#0 0x00007f5ed4df9425 in raise () from /lib/x86_64-linux-gnu/libc.so.6
#1 0x00007f5ed4dfcb8b in abort () from /lib/x86_64-linux-gnu/libc.so.6
#2 0x00007f5ed4df20ee in ?? () from /lib/x86_64-linux-gnu/libc.so.6
#3 0x00007f5ed4df2192 in __assert_fail () from /lib/x86_64-linux-gnu/libc.so.6
#4 0x00000000005d1bc8 in uv__stream_io (loop=<optimized out>, w=<optimized out>, events=<optimized out>) at ../deps/uv/src/unix/stream.c:729
#5 0x00000000005c6ac2 in ev_invoke_pending (loop=0xdb34c0 <default_loop_struct>) at ../deps/uv/src/unix/ev/ev.c:2145
#6 0x00000000005c2986 in uv__poll (loop=0xdb27e0 <default_loop_struct>) at ../deps/uv/src/unix/core.c:246
#7 uv__run (loop=0xdb27e0 <default_loop_struct>) at ../deps/uv/src/unix/core.c:257
#8 0x00000000005c2c60 in uv_run (loop=0xdb27e0 <default_loop_struct>) at ../deps/uv/src/unix/core.c:265
#9 0x000000000057d9f7 in node::Start(int, char**) ()
#10 0x00007f5ed4de476d in __libc_start_main () from /lib/x86_64-linux-gnu/libc.so.6
#11 0x0000000000575245 in _start ()
#0 0x00000000006b13b8 in v8::Object::SetHiddenValue(v8::Handle<v8::String>, v8::Handle<v8::Value>) ()
#1 0x0000000000593f5a in node::SlabAllocator::Allocate(v8::Handle<v8::Object>, unsigned int) ()
#2 0x0000000000591d04 in node::StreamWrap::OnAlloc(uv_handle_s*, unsigned long) ()
#3 0x00000000005d08fb in uv__read (stream=0x1fa7f90) at ../deps/uv/src/unix/stream.c:575
#4 0x00000000005d1a1a in uv__stream_io (loop=<optimized out>, w=<optimized out>, events=<optimized out>) at ../deps/uv/src/unix/stream.c:745
#5 0x00000000005c6ac2 in ev_invoke_pending (loop=0xdb34c0 <default_loop_struct>) at ../deps/uv/src/unix/ev/ev.c:2145
#6 0x00000000005c29df in uv__poll (loop=0xdb27e0 <default_loop_struct>) at ../deps/uv/src/unix/core.c:248
#7 uv__run (loop=0xdb27e0 <default_loop_struct>) at ../deps/uv/src/unix/core.c:257
#8 0x00000000005c2c60 in uv_run (loop=0xdb27e0 <default_loop_struct>) at ../deps/uv/src/unix/core.c:265
#9 0x000000000057d9f7 in node::Start(int, char**) ()
#10 0x00007f065aa1176d in __libc_start_main () from /lib/x86_64-linux-gnu/libc.so.6
#11 0x0000000000575245 in _start ()
More often than not I get one of the first two errors – ie, no stack trace. These all occurred while trying to resize 6 or so images – occasionally they all succeed without error, but usually it seg faults after the first one or two have been resized.
How on earth do I go about debugging this?
In the unit test for the node-vips plugin there's a comment that reads:
this test will crash if vips is compiled with imagemagick support because imagemagick crashes when called from libeio
Why is this? Is this still true? I thought ImageMagick was perfectly thread-safe, what about it makes it not safe to be called from libeio/libuv?