I'm running SPECjvm98 on a vanilla main_baseline build. I'm getting
occasional

    # assert(thread->osthread()->is_self_suspended(), "Expected self suspension")

I'm running on a P3-700, running Windohs NT 4.0 SP6+, with

    Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.0-beta3-b82)

and a command line of

    main_baseline\compiler2\bin\java_g -server -Xss1m -Xbatch -Xms32m -Xmx32m SpecApplication -s100 -a -m5 -M5 _200_check _227_mtrt _202_jess _201_compress _209_db _222_mpegaudio _228_jack _213_javac

It doesn't fail every time. I've just run it 10 times and gotten 3
failures at 3 different points:

    ======= _222_mpegaudio Starting =======
    Run 0 start. Total memory=33226752 free memory=31788952
    MPEG Audio - Decoding input/track2.mp3 1 time

    MPEG Layer-3 Audio - Java Decoder Implementation
       (c) 1997 Fraunhofer IIS, Erlangen/Germany

    #
    # HotSpot Virtual Machine Error, assertion failure
    # Please report this error at
    # http://java.sun.com/cgi-bin/bugreport.cgi
    #
    # Java VM: Java HotSpot(TM) Server VM (1.4-internal-debug mixed mode)
    #
    # assert(thread->osthread()->is_self_suspended(), "Expected self suspension")
    #
    # Error ID: D:\pbk\Workspaces\win32_i486\main_baseline\src\share\vm\runtime\safepoint.cpp, 877
    #
    # Problematic Thread: prio=5 tid=0x0076EB38 nid=0x161 runnable
    #

    ======= _227_mtrt 10% execution - timing ignored
    Run 2 start. Total memory=33226752 free memory=23145696
    +0 to 99 by 200
    +100 to 199 by 200
    #
    # HotSpot Virtual Machine Error, assertion failure
    # Please report this error at
    # http://java.sun.com/cgi-bin/bugreport.cgi
    #
    # Java VM: Java HotSpot(TM) Server VM (1.4-internal-debug mixed mode)
    #
    # assert(thread->osthread()->is_self_suspended(), "Expected self suspension")
    #
    # Error happened during: generation collection for allocation
    #
    # Error ID: D:\pbk\Workspaces\win32_i486\main_baseline\src\share\vm\runtime\safepoint.cpp, 877
    #
    # Problematic Thread: prio=5 tid=0x0078D248 nid=0x15b waiting on monitor
    #

    ======= _227_mtrt 10% execution - timing ignored
    Run 1 start. Total memory=33226752 free memory=15154992
    +0 to 99 by 200
    +100 to 199 by 200
    #
    # HotSpot Virtual Machine Error, assertion failure
    # Please report this error at
    # http://java.sun.com/cgi-bin/bugreport.cgi
    #
    # Java VM: Java HotSpot(TM) Server VM (1.4-internal-debug mixed mode)
    #
    # assert(thread->osthread()->is_self_suspended(), "Expected self suspension")
    #
    # Error happened during: generation collection for allocation
    #
    # Error ID: D:\pbk\Workspaces\win32_i486\main_baseline\src\share\vm\runtime\safepoint.cpp, 877
    #
    # Problematic Thread: prio=5 tid=0x007B5498 nid=0x188 runnable
    #

I don't think it has anything to do with GC, even though 2 of those say
it happened during collection for allocation. I think it's just that
GC causes safepoints. I don't know if it only happens with -server,
or only on Windohs. Obviously it only fails the assert in debug builds.
(Don't forget the -Xss1m when running debug server builds!)

###@###.### 2001-10-09

I just caught one of these inside of VC++, so I can give you some more
information. The threads list is (transcribed by hand):

    Thread ID Suspend Priority Location
    000000c0 0 9 [CompileQueue::get]
    0000013b 1 9
   *00000153 0 9 $L113467
    00000162 0 15 [os::signal_wait]
    00000163 0 11 [ObjectMonitor::wait]
    00000166 0 9 [CompileQueue::get]
    0000016c 0 15 [ObjectMonitor::wait]
    00000176 0 15 [SuspendCheckerThread::run]
    00000183 0 15 [WatcherThread::run]

and the thread that's failing the assert is at

    CompiledCodeSafepointHandler::setup(ThreadSafepointState * 0x00764668, nmethod * 0x00b7cbc8) line 877 + 47 bytes
    ThreadSafepointState::roll_forward(ThreadSafepointState::suspend_type _compiled_safepoint, nmethod * 0x00b7cbc8, int 0) line 659
    ThreadSafepointState::examine_state_of_thread(int 0) line 595
    SafepointSynchronize::begin() line 83
    VMThread::loop() line 300
    VMThread::run() line 189
    _start(Thread * 0x0076eee8) line 256
    _threadstartex(void * 0x0076eb70) line 212 + 13 bytes
    KERNEL32! 77f04ef0()

###@###.### 2001-10-09