[Oberon] New BB release

Ulrike Glavitsch ulrike.glavitsch at inf.ethz.ch
Tue Jun 26 11:22:18 MEST 2007

Dear BB/AOS-users,

a new crazy-fresh release of BB/AOS is ready for download under 
After months of development of a new GC that uses meta data for stack 
inspection a first version of AOS with the new GC is available now.
We found that the old GC that uses a heuristic for stack inspection can 
block the whole system. The test program that causes such a system 
freeze is attached to this mail (please use the commands Test.TestStack~ 
to start the test, i.e. creation of 8000 threads with some LONGINT stack 
values, Test.StartGC 1000 ~ to initiate GC calls and Test.StopGC to stop 
the GC calls). The system with the old GC will freeze after a few GC 
calls. The new GC does not have this system freeze problem.
A few little things still need to be improved with the new GC. These are 
1) Use of meta data for kernel stacks (kernel stacks are still inspected 
using the heuristic in the new GC)
2) Inspection of the awaiting queues (solved neither in the old nor in 
the new GC)

Please use this release with caution. If you encounter problems with it 
please report them to me.

Best regards,

Ulla Glavitsch

ETH Zürich
Ulrike Glavitsch Eggler
Institut für Computersysteme
Clausiusstrasse 59
CH-8092 Zürich
Tel.: +41 44 632 70 49
Fax : +41 44 632 13 07

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