Hi Long,
I assume you are using Native X10 (x10c++). The File IO error handling
is quite basic and reports any error on calling fopen as
'FileNotFoundException' - even if the problem is e.g. too many open file
descriptors.
The File.lines() method silently creates a FileReader and uses it to
open and read the file. However, if you do not explicitly close the
reader, the fd will remain open until whenever the FileReader is garbage
collected (at some arbitrary future time). Therefore the net result of
your code is to open file descriptors until the system limit is reached
and fopen crashes with EMFILE.
To fix this, try:
var file_list:ArrayList[String]=new ArrayList[String]();
for( f1 in (0..1000)){
for(f2 in (0..30)){
val f_name=f1.toString()+"_"+f2.toString();
val file=new File(f_name);
if(file.exists()) {
val reader = file.openRead();
//Console.OUT.println(f1+"_"+f2);
for(s in reader.lines()){
file_list.add(s);
}
reader.close();
}
}
}
Cheers,
Josh
On 08/01/13 11:01, Long Cheng wrote:
> Dear all,
>
> I tried to read a large number of files into an ArrayList with the
> following code:
>
> var file_list:ArrayList[String]=new ArrayList[String]();
> for( f1 in (0..1000)){
> for(f2 in (0..30)){
> val f_name=f1.toString()+"_"+f2.toString();
> val file=new File(f_name);
> if(file.exists()) {
> //Console.OUT.println(f1+"_"+f2);
> for(s in file.lines()){
> file_list.add(s);
> }
> }
> }
> }
>
> But in the implementations I always meet the error:
>
> Uncaught exception at place 0: x10.lang.MultipleExceptions
> x10.io.FileNotFoundException: 50_22
> at x10::lang::CheckedThrowable::fillInStackTrace()
> at x10aux::throwException(x10::lang::CheckedThrowable*)
> at
> x10::io::FileReader__FileInputStream::_constructor(x10::lang::String*)
> at x10::io::FileReader__FileInputStream::_make(x10::lang::String*)
> at x10::io::FileReader::_constructor(x10::io::File*)
> at x10::io::FileReader::_make(x10::io::File*)
> at x10::io::File::openRead()
> at x10::io::File::lines()
> at active_read::main(x10::array::Array<x10::lang::String*>*)
> at x10aux::BootStrapClosure::__apply()
> at x10::lang::VoidFun_0_0::__apply(x10::lang::VoidFun_0_0*)
> at x10::lang::Activity::run()
> at x10::lang::Runtime__Worker::loop()
> at x10::lang::Runtime__Worker::__apply()
> at x10::lang::Runtime__Pool::__apply(int)
> at x10::lang::Runtime::start(x10::lang::VoidFun_0_0*)
> at
> at GC_inner_start_routine
> at GC_call_with_stack_base
> at
> at clone
>
> Actually the file 50_22 exists. I tried to initialized the size of the
> arraylist with a number large enough, and close the filereader after
> reading each file as well, but still meet the same error. Is there any
> comment about this?
>
> Thanks,
>
> Long
>
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