[Mono-dev] Problem handling more the 1024 file handle

[Torello Querci]

Sorry, You are right .... I'm on 32bit arch

2011/11/4 Robert Jordan <robertj at gmx.net>:
> On 04.11.2011 10:17, Torello Querci wrote:
>> This is the first test that I realized.
>> On the same machine, same kernel .... same calls ....
>
> You don't say which Mono arch you're using. On 32 bit,
> the following might not be correct:
>
>        struct rlimit {
>                public IntPtr rlimit_cur;
>                public IntPtr rlimit_max;
>        }
>
> because rlim_t is 8 byte long whereas IntPtr is 4 bytes.
> This is because Mono is compiled with LARGEFILE64 support.
>
> Robert
>
>
>>
>> Below the source code:
>>
>> =====================================================================
>> #include<linux/resource.h>
>>
>> //#include<stdlib.h>
>> #include<stdio.h>
>>
>>
>> int main(int argc, char* argv[]) {
>>
>>      FILE** fp;
>>      int nFiles = atoi(argv[1]);
>>      int i;
>>      char filename[1024];
>>
>>      if (argc!=2) {
>>          printf("Error. You need to specify the number of file that
>> need to create.\n");
>>          return -1;
>>      }
>>
>>      struct rlimit data;
>>
>>      data.rlim_cur = 20000;
>>      data.rlim_max = 20000;
>>
>>      i = setrlimit (RLIMIT_NOFILE,&data);
>>      if (i != 0) {
>>          printf ("Error during changine files limits.\n");
>>          return 1;
>>      }
>>
>>      fp = calloc (nFiles, sizeof(FILE*));
>>
>>      for (i=0; i<nFiles; ++i) {
>>          sprintf (filename, "file%i.out", i);
>>
>>          fp[i] = fopen (filename, "w+");
>>          if (fp [i] == NULL) {
>>              printf ("Error in %s file creation.\n", filename);
>>              return -1;
>>          }
>>      }
>>
>> }
>>
>> =============================================================
>>
>> 2011/11/4 Alan<alan.mcgovern at gmail.com>:
>>> Hi,
>>> Mono itself has no trouble opening 1000's of files. Would you be able to
>>> create an equivalent C program and see if that works as expected? My guess
>>> would be that the equivalent C program will fail in the same way. If it does
>>> not, then it's likely to be a mono bug.
>>> Alan
>>>
>>> On 4 November 2011 07:19, Torello Querci<tquerci at gmail.com>  wrote:
>>>>
>>>> Hi al,
>>>>
>>>> trying to handle more that 1024 handle file I got an exception even if
>>>> I increase the max number of file limit using "setrlimit". The example
>>>> source code below.
>>>> Of course mono have the right pcap permission.
>>>>
>>>> Using strace on both this code and no setrlimit version code I have
>>>> some differences.
>>>> On the no setrlimit version I have this syscall:
>>>>
>>>> open("file1021.out", O_WRONLY|O_CREAT|O_TRUNC|O_LARGEFILE, 0666) = -1
>>>> EMFILE (Too many open files)
>>>>
>>>> and this seems to be correct.
>>>> On the setrlimit version code I have this syscalls:
>>>>
>>>> open("file1021.out", O_WRONLY|O_CREAT|O_TRUNC|O_LARGEFILE, 0666) = 1024
>>>> close(1024)                             = 0
>>>>
>>>> so seems that mono close the file because open  return value is 1024.
>>>>
>>>> Is this a bug, a feature, or something else?
>>>>
>>>>
>>>> ==================================================================================================================
>>>> using System;
>>>> using System.IO;
>>>> using System.Text;
>>>> using System.Runtime.InteropServices;
>>>>
>>>> namespace TestFiles
>>>> {
>>>>
>>>>         struct rlimit {
>>>>                 public IntPtr rlimit_cur;
>>>>                 public IntPtr rlimit_max;
>>>>         }
>>>>
>>>>         class MainClass
>>>>         {
>>>>                 public static unsafe void Main (string[] args)
>>>>                 {
>>>>                         FileStream[] streams;
>>>>                         string path;
>>>>                         if (args.Length == 0) {
>>>>                                 Console.WriteLine ("You need to specify the
>>>> number of files that
>>>> needs to be created.");
>>>>                                 return;
>>>>                         }
>>>>
>>>>                         int nFiles = Int32.Parse (args[0]);
>>>>
>>>>                         streams = new FileStream[nFiles];
>>>>
>>>>                         rlimit data = new rlimit ();
>>>>                         data.rlimit_cur = (IntPtr) 20000;
>>>>                         data.rlimit_max = (IntPtr) 20000;
>>>>
>>>>                         int result = setrlimit (RLIMIT_NOFILE,&data);
>>>>                         if (result != 0) {
>>>>                                 throw new Exception ("Cannot change limit
>>>> on open files");
>>>>                         }
>>>>
>>>>                         for (int i=0; i<nFiles; ++i) {
>>>>                                 path = string.Format ("file{0}.out", i);
>>>>                                 try {
>>>>                                         streams[i] = File.Open(path,
>>>> FileMode.Create, FileAccess.Write,
>>>> FileShare.None);
>>>>                                 } catch (Exception ex) {
>>>>                                         Console.WriteLine ("Unable to write
>>>> file {0}", path);
>>>>                                         Console.WriteLine (ex.Message);
>>>>                                         Console.WriteLine (ex.StackTrace);
>>>>                                         return;
>>>>                                 }
>>>>                         }
>>>>                 }
>>>>
>>>>                 const int RLIMIT_NOFILE = 7;
>>>>
>>>>                 [DllImport ("libc", SetLastError = true)]
>>>>                 unsafe extern static int setrlimit(int resource, rlimit*
>>>> rlim);
>>>>
>>>>         }
>>>> }
>>>> _______________________________________________
>>>> Mono-devel-list mailing list
>>>> Mono-devel-list at lists.ximian.com
>>>> http://lists.ximian.com/mailman/listinfo/mono-devel-list
>>>
>>>
>
>
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