I tried commenting out that line, and I get: 
...
ioctl(0, SNDCTL_TMR_TIMEBASE or TCGETS, 0xbf99e438) = -1 EINVAL (Inval
+id argument)
fstat64(0, {st_mode=S_IFIFO|0600, st_size=0, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1,
+ 0) = 0xb7b62000
read(0, "load(\'jslint.js\');\nfoo=0;\nEND\nqu"..., 1024) = 38
read(0,

[download]

So, it's not even to the point where it's processing the information coming from perl. It hasn't even loaded jslint.js yet. I think I get it. So let's see if I'm understanding this properly:

While perl may be properly autoflushing, the interpreter is still buffering its read. Since the socket(?) is still open, it doesn't know to close it and flush.

When it does close it and flush, it is acutally waiting to make use of the rest of the string ("foo=0;\nEND\n") AFTER the readline loop. So it would be as if I had done something like this (which also freezes): 

$ echo -e "load('jslint.js');\nfoo=0;\nEND\n" |/usr/bin/js

[download]

Hence, the rock and hard place are that, if I don't close $JSWRITE in a timely manner, the interpreter won't know to flush its read buffer and continue, but if I do close $JSWRITE, there's nothing for the readline() loop to read from anymore.

So it's not so much that my Perl code isn't outputting correctly, it's that the interpreter is accepting/buffering input in an incompatible way?

In reply to Re^2: Calling strace -f by Socrates
in thread Diagnosing blocking io (or: finding the WHY of my Open2 woes). by Socrates

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