Thread freezes on SLAVE START/STOP

[Pavel Merdine]

>Description:
        A  thread  in  which SLAVE START/STOP was issued freezes. E.g.
        'mysql'  can  be  only  exited  by  pressing Ctrl-C. Actually,
        only first command is executed. Next are ignored.
        Sideeffects  tends to be table files corruption, 'master.info'
        erase.
        Now (4.0.11) they freeze even after server full restart.
        We tried different mysql versions: 4.0.7, 4.0.8, 4.0.11
>How-To-Repeat:
        The  exact  conditions  are  unknown.  Sometimes they work. It
        looks  like  fault  happens after any replication error. (E.g.
        table update error). But I'm not sure.
>Fix:
        -

>Submitter-Id:
>Originator:    Pavel Merdine
>Organization:  Fotki Inc.
>MySQL support: none
>Synopsis:      SLAVE START/STOP freezes
>Severity:      serious
>Priority:      medium
>Category:      mysql
>Class:         sw-bug
>Release:       mysql-4.0.11-gamma-standard (Official MySQL-standard binary)

>C compiler:    2.95.4
>C++ compiler:  2.95.4
>Environment:
        CPU:  Dual  Pentium III/Pentium III Xeon (451.03-MHz)
        avail memory = 777900032 (759668K bytes)
        <machine, os, target, libraries (multiple lines)>
        System:  FreeBSD  dev.fotki.com  4.7-STABLE FreeBSD 4.7-STABLE
        #1: Thu Jan  9 17:40:50 GMT 2003 
        Some  paths:  /usr/bin/perl /usr/bin/make /usr/local/bin/gmake
        /usr/bin/gcc /usr/bin/cc 
        GCC: Using builtin specs.
        gcc version 2.95.4 20020320 [FreeBSD]
        Compilation  info:  CC='gcc'   CFLAGS='-DHAVE_BROKEN_REALPATH'
        CXX='g++'  CXXFLAGS=''  LDFLAGS=''  ASFLAGS='' 
        LIBC:
        -r--r--r--  1 root  wheel  1218496 Oct  9 08:43 /usr/lib/libc.a
        lrwxrwxrwx   1 root  wheel  9 Jan  8 05:16 /usr/lib/libc.so ->
        libc.so.4 
        -r--r--r--  1 root  wheel  574916 Oct  9 08:43 /usr/lib/libc.so.4
        Configure  command:  ./configure  '--prefix=/usr/local/mysql'
        '--with-comment=Official      MySQL-standard      binary'
        '--with-extra-charsets=complex'
        '--with-server-suffix=-standard' '--enable-thread-safe-client'
        '--enable-local-infile'          '--enable-assembler'
        '--with-named-z-libs=not-used'        '--disable-shared'
        '--with-innodb' 'CFLAGS=-DHAVE_BROKEN_REALPATH'