A20 - Computer Sharing - Crash 2nd User

Repeatable crash - sometimes 2 Logos users share 1 computer - A20 running for 1 user - switch user to different account => Launch A20 => crash (before logos.log and indexer.log files created). Attached zip file has crash report and corresponding console message selections (different per user).

2783.A20-Crash-Running-Other-User.zip

Observation: Apple Mail allows 2 users to simultaneously run on same computer with different user settings (similar per user ~/Library setup as Logos 4).

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Thomas Ball

KS4J:

I'll file a bug report for this.

Tom Philpot (Faithlife)

KSFJ,

This won't work in A20 and prior due to a way the Indexer and Logos 4 app communicate via IPC. We're using shared memory segments in the kernel which are linked to the specific Logos4 account. Only the OS user who creates them has access to them, so when the second OS user starts up with the same Logos 4 account, you get the EACCESS because the second OS user doesn't have R/W access to the shared memory segment.

This might work in A21 since we've switched to using file mapped shared memory for IPC instead of kernel shared memory segments. So in A21, the Logos 4 and the indexer for OS user 1 are communicating via different IPC channels than the Logos 4 and indexer processes for OS user 2, even if they are using the same Logos 4 account.

I haven't tested it, but give it a shot on Tuesday when A21 comes out and see if it works. If it doesn't I'll investigate further.

Tom

Thomas Ball

https://community.logos.com/discussion/comment/132606#Comment_132606

KS4J:

I am able to have A20 open on one account and A21 on the other.

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https://community.logos.com/discussion/comment/132606#Comment_132606

KSFJ,

This won't work in A20 and prior due to a way the Indexer and Logos 4 app communicate via IPC. We're using shared memory segments in the kernel which are linked to the specific Logos4 account. Only the OS user who creates them has access to them, so when the second OS user starts up with the same Logos 4 account, you get the EACCESS because the second OS user doesn't have R/W access to the shared memory segment.

This might work in A21 since we've switched to using file mapped shared memory for IPC instead of kernel shared memory segments. So in A21, the Logos 4 and the indexer for OS user 1 are communicating via different IPC channels than the Logos 4 and indexer processes for OS user 2, even if they are using the same Logos 4 account.

I haven't tested it, but give it a shot on Tuesday when A21 comes out and see if it works. If it doesn't I'll investigate further.

Tom

Thanks for the technical insight. Used "ipcs -a" to see 4 shared memory segments - wonder about id and key being different for different OS users ? (semaphores faster for IPC and avoid file system caching/latency issues)

Observation: Oracle database processes on unix and linux use shared memory segments along with semaphores for IPC. With same OS user and group (or different OS user and group in different Oracle Homes), more than 1 database instance can share memory as long as total shared memory requested by all database instances is less than available shared memory. Also all database instances must have different System Identifiers (SID's) - so each set of processes uses appropriate shared memory and semaphores for a particular instance.

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