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Message: [QUOTE="H J van Rooyen, post: 1896002"] | On Thu, 27 Jul 2006 08:48:37 -0400, Jean-Paul Calderone | <exarkun@divmod.com> declaimed the following in comp.lang.python: | | > | > If a thread never performs any I/O operations, signal handlers will still | > get invokes on the arrival of a signal. | > | I thought I'd qualified that scenario -- from the point of view of | one OS I've programmed, where signals were only handled as part of the | I/O system (or, in more general, as part of any /blocking/ system call | from an application -- not even a <ctrl-c> would have an effect unless | the application invoked a blocking call, or explicitly polled the signal | bits of its task header) | -- I have to support this - a processor is only doing one instruction at a time, if its not a multi core device - and the only ways that the "operating system part" of the system can get control back from the *user program part* of the system are: a) when the User makes an OS call (like blocking I/O, or any OS request) b) when the user code is interrupted by some hardware thingy and the OS part handles the interrupt. So on a processor that does not have protected instructions - if an idiot writes something to the following effect : *instructions to disable interrupts* followed by : *instructions that go into an infinite loop AND that make no OS calls* the whole bang shoot stops dead - Reset your machine... Dennis - did your OS not have a ticker running? - Hendrik [/QUOTE]