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  1. JDK
  2. JDK-4935095

JNI call to getdtablesize() returns hard limit instead of soft limit

    Details

    • Subcomponent:
    • CPU:
      generic
    • OS:
      solaris_9

      Description


      JNI call to getdtablesize() returns hard limit instead of soft limit.
      A corresponding C program however behaves as expected and returns the
      soft limit, as documented in the man page.

      The problem is easily reproducible:

      1. Testcase
      -----------

       The testcase consists of the following files:

      % ls -l
      total 8
      -rw-r--r-- 1 tl15687 sun 772 Oct 9 15:22 Makefile
      -rw-r--r-- 1 tl15687 sun 404 Oct 9 12:49 test.java
      -rw-r--r-- 1 tl15687 sun 244 Oct 9 13:07 testImpl.c
      -rw-r--r-- 1 tl15687 sun 127 Oct 9 13:24 tst.c
      %

       "tst.c" is the C program, which returns the soft limit as expected.
       Java class "test" makes use of "testImpl.c", which translates into
       "libtst.so". The JNI call returns the hard limit unexpectedly.


      % more tst.c
      #include <stdio.h>
      #include <unistd.h>

      int main() {

       int i = getdtablesize();
       printf("getdtablesize: %d\n", i);
       exit(0);
      }
      %

      % more test.java

      public class test
      {
        public native int getdtablesize();

        static {
            System.loadLibrary("tst");
        }

        public static void main(String[] args) {

          int i;
          test tst = new test();

          i = 0;

          System.out.print("-------- Before JNI: ");
          System.out.println("i= " + i);

          i = tst.getdtablesize();

          System.out.print("-------- After JNI: ");
          System.out.println("i= " + i);

        }
      }
      %

      % more testImpl.c
      #include <stdio.h>
      #include <jni.h>
      #include <unistd.h>
      #include "test.h"

      JNIEXPORT jint JNICALL Java_test_getdtablesize (JNIEnv * env, jobject obj)
      {
        jint ci;

        printf("JNI get_dtablesize .... \n");

        ci = getdtablesize();
        return ci;
      }
      %


      % more Makefile

      CC=/opt/SUNWspro/bin/CC
      C=/opt/SUNWspro/bin/cc
      JAVA=/j2sdk1_3_1_08
      JAVA=/j2sdk1.4.1_05
      JAVA=/j2sdk1.4.2_01

      LIBRARIES = -lc

      INCJAVA = $(JAVA)/include
      INCJAVASOLARIS = $(JAVA)/include/solaris

      CPPFLAGS =-I$(INCJAVA) -I$(INCJAVASOLARIS)


      CCFLAGS = -V

      #all: gen sign comp run
      all: gen comp run

      gen:
              $(JAVA)/bin/javac test.java
              $(JAVA)/bin/javah -jni test
      comp:
              $(CC) -G $(CCFLAGS) $(CPPFLAGS) testImpl.c -o libtst.so $(LIBRARIES)
              $(C) $(CCFLAGS) tst.c -o tst
      run:
              ./tst
              ulimit -n
              $(JAVA)/bin/java test
              ulimit -Hn
      sign:
              $(JAVA)/bin/javap -s -p test > signature.txt

      clean:
              rm -rf libtst.so tst *.class *.h signature.txt
      %


      2. Compile
      ----------
      % make clean
      rm -rf libtst.so tst *.class *.h signature.txt
      % make gen
      /j2sdk1.4.2_01/bin/javac test.java
      /j2sdk1.4.2_01/bin/javah -jni test
      % make comp
      /opt/SUNWspro/bin/CC -G -V -I/j2sdk1.4.2_01/include -I/j2sdk1.4.2_01/include/solaris testImpl.c -o libtst.so -lc
      CC: Sun WorkShop 6 update 2 C++ 5.3 Patch 111685-15 2003/05/14
      ccfe: Sun WorkShop 6 update 2 C++ 5.3 Patch 111685-15 2003/05/14
      CClink: Sun WorkShop 6 update 2 C++ 5.3 Patch 111685-15 2003/05/14
      CC: Sun WorkShop 6 update 2 C++ 5.3 Patch 111685-15 2003/05/14
      /opt/SUNWspro/bin/../WS6U2/bin/c++filt: Sun WorkShop 6 update 2 C++ 5.3 2001/05/15
      ld: Software Generation Utilities - Solaris Link Editors: 5.9-1.343
      /opt/SUNWspro/bin/cc -V tst.c -o tst
      cc: Sun WorkShop 6 update 2 C 5.3 Patch 111679-12 2003/05/18
      acomp: Sun WorkShop 6 update 2 C 5.3 Patch 111679-12 2003/05/18
      ld: Software Generation Utilities - Solaris Link Editors: 5.9-1.343
      %


      3. Run
      ------
      3.1 Run on Solaris 7
      --------------------
      % setenv LD_LIBRARY_PATH .:/usr/lib
      % make run
      ./tst
      getdtablesize: 64
      ulimit -n
      64
      /j2sdk1.4.2_01/bin/java test
      -------- Before JNI: i= 0
      JNI get_dtablesize ....
      -------- After JNI: i= 1024
      ulimit -Hn
      1024
      %


      3.2 Run on Solaris 8
      --------------------
      % setenv LD_LIBRARY_PATH .:/usr/lib
      % make run
      ./tst
      getdtablesize: 256
      ulimit -n
      256
      /net/cores/tsc/Applix/java/JDK/j2sdk1.4.2_01/bin/java test
      -------- Before JNI: i= 0
      JNI get_dtablesize ....
      -------- After JNI: i= 1024
      ulimit -Hn
      1024
      %


      3.3 Run on Solaris 9
      --------------------
      % setenv LD_LIBRARY_PATH .:/usr/lib
      % make run
      ./tst
      getdtablesize: 256
      ulimit -n
      256
      /net/cores/tsc/Applix/java/JDK/j2sdk1.4.2_01/bin/java test
      -------- Before JNI: i= 0
      JNI get_dtablesize ....
      -------- After JNI: i= 65536
      ulimit -Hn
      65536
      %


      4. Compare to man page
      ----------------------
      % man getdtablesize
      Reformatting page. Please Wait... done

      Standard C Library Functions getdtablesize(3C)

      NAME
           getdtablesize - get the file descriptor table size

      SYNOPSIS
           #include <unistd.h>

           int getdtablesize(void);

      DESCRIPTION
           The getdtablesize() function is equivalent to getrlimit(2)
           with the RLIMIT_NOFILE option.

      RETURN VALUES
           The getdtablesize() function returns the current soft limit
           as if obtained from a call to getrlimit() with the
           RLIMIT_NOFILE option.
      [ ... ]


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            • Assignee:
              acorn Karen Kinnear (Inactive)
              Reporter:
              thlenz Thomas Lenz (Inactive)
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              • Created:
                Updated:
                Resolved:
                Imported:
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