Re: [ZODB-Dev] ZEO invalidation message transaction-inbound or outbound
On 12/01/2012 11:22 AM, Andreas Jung wrote: Jim Fulton wrote: On Fri, Nov 30, 2012 at 1:37 AM, Andreas Jung li...@zopyx.com wrote: a customer made the observation that that ZEO clients became inconsistent after some time (large CMF-based application running on Zope 2.12 afaik). Customer made some investigation and noticed that the ZEO invalidations have been queued (in some cases for hours). I can't imagine invalidations being queued for many seconds, much less hours without some serious network pathology. How did they come to this conclusion? I am only asking on customer behalf. This was their observation. Did the customer mean to say that the clients becomes stale (not inconsistent)? I've seen ZEO clients become stale due to network instability. The clients caught up the moment they changed something. This was years ago, though. Shane ___ For more information about ZODB, see http://zodb.org/ ZODB-Dev mailing list - ZODB-Dev@zope.org https://mail.zope.org/mailman/listinfo/zodb-dev
Re: [ZODB-Dev] ZEO invalidation message transaction-inbound or outbound
On Mon, Dec 3, 2012 at 2:35 PM, Shane Hathaway sh...@hathawaymix.org wrote: I've seen ZEO clients become stale due to network instability. The clients caught up the moment they changed something. This was years ago, though. ZEO clients now send keep-alive messages to the storage server to prevent this from happening. Jim -- Jim Fulton http://www.linkedin.com/in/jimfulton Jerky is better than bacon! http://zo.pe/Kqm ___ For more information about ZODB, see http://zodb.org/ ZODB-Dev mailing list - ZODB-Dev@zope.org https://mail.zope.org/mailman/listinfo/zodb-dev
Re: [ZODB-Dev] ZEO invalidation message transaction-inbound or outbound
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Jim Fulton wrote: On Fri, Nov 30, 2012 at 1:37 AM, Andreas Jung li...@zopyx.com wrote: a customer made the observation that that ZEO clients became inconsistent after some time (large CMF-based application running on Zope 2.12 afaik). Customer made some investigation and noticed that the ZEO invalidations have been queued (in some cases for hours). I can't imagine invalidations being queued for many seconds, much less hours without some serious network pathology. How did they come to this conclusion? I am only asking on customer behalf. This was their observation. - -aj -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.11 (Darwin) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iQGUBAEBAgAGBQJQukrrAAoJEADcfz7u4AZjY+sLwOf7CL6Iv5kzceQXh1TLz7Bn xXtmkfsrIY2uK6lLTNBqL1qhi12yt4Ooo/b+w0WEOwEQj6iAQxYUyIutzYhRkUou pneM4pzgRFGsriqCQnWe2rz0k+O8DwSFCkeBFxDdG/f9sZlYqXxWPJ03LgUOhxyE aPOs1dPlpyXkmvnXchU4xzeh9loE0kjA268/8RqTFhW+hbn3hzW0hqkWb8uLKGFt 223WWJg4rkHL4S7L6yXVqQtWomYBU/AVzUTOD2rRmnrq8/UFAFT+pQ6SZYCSPt6K EgSOb2LxWkimF8bMT0f25+Pqc041T7Ggmot707YicE1KzTWznxo5+YePlg27GYXp WhpRapGiINlBvQC91bNNMmzFvpB839jdGqjIkyOYP2OjPbEFxxr5QJPSCyzUiWgw 4ngWEbxGVMtA6vV1CutfCSs0+b4IDFBiXQQ+i4tUAnxa0MFRrybx5hTY0j/8qgNp +oomrZb11xRvEeFkkEkbXk5Gca2cz9U= =SlhL -END PGP SIGNATURE- attachment: lists.vcf___ For more information about ZODB, see http://zodb.org/ ZODB-Dev mailing list - ZODB-Dev@zope.org https://mail.zope.org/mailman/listinfo/zodb-dev
Re: [ZODB-Dev] ZEO invalidation message transaction-inbound or outbound
On Fri, Nov 30, 2012 at 1:37 AM, Andreas Jung li...@zopyx.com wrote: a customer made the observation that that ZEO clients became inconsistent after some time (large CMF-based application running on Zope 2.12 afaik). Customer made some investigation and noticed that the ZEO invalidations have been queued (in some cases for hours). I can't imagine invalidations being queued for many seconds, much less hours without some serious network pathology. How did they come to this conclusion? ..so the overall state of the ZEO clients became inconsistent. Aren't ZEO invalidation messages supposed to be transmitted within the current transaction (and outbound as it seems to happen here). No. Invalidations (and all other data) are queued for transmission over the network. Isn't a ZEO cluster to be completely consistent at any time? Each client has a consistent view of the database, but not necessarily an up-to-date one. Differene clients may have views of the database as it was at (usually slightly) different points time, depending on which data they've recieved. It's not practical for all clients to have precisely the same view of the database as each other, although they should differ by seconds, or less. The only way I can see clients having views of the database far out of sync with the server is if the clients are disconncted. A ZEO client can continue functioning normally from a server while disconnected as long as it doesn't write anything and has all the data it needs in its cache. It has a consistent view of the database, but not an up-to-date one. Jim -- Jim Fulton http://www.linkedin.com/in/jimfulton Jerky is better than bacon! http://zo.pe/Kqm ___ For more information about ZODB, see http://zodb.org/ ZODB-Dev mailing list - ZODB-Dev@zope.org https://mail.zope.org/mailman/listinfo/zodb-dev
[ZODB-Dev] ZEO invalidation message transaction-inbound or outbound
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Hi there, a customer made the observation that that ZEO clients became inconsistent after some time (large CMF-based application running on Zope 2.12 afaik). Customer made some investigation and noticed that the ZEO invalidations have been queued (in some cases for hours)...so the overall state of the ZEO clients became inconsistent. Aren't ZEO invalidation messages supposed to be transmitted within the current transaction (and outbound as it seems to happen here). Isn't a ZEO cluster to be completely consistent at any time? This smeels like eventually consistency as we know it from noSQL databases but I always that a ZEO cluster would be completely consistent!? - -aj -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.11 (Darwin) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iQGUBAEBAgAGBQJQuFQZAAoJEADcfz7u4AZjXhoLv1ubv4/4qnAtrUXl0kgvYPpu /Rns1EjzLc4THnV7pVU1+dZTYZO0mr3bIOG6PBXI0fG/XjOfAV1pyX+pLWCo7xr4 xGnMLdqDQf5C6bCbqWyUT5aD/UPi82SExoKqEDGKVT1rzSuBXkSRuYdAtYc0ZtUs 0h6FNxIMf2kRsDisXgSadzy2TSbk50l6o0DwNf31R7Ox7ZM1ko08xxLK20BRs+21 Tsw7c/gUeRpQPpKFzHeeLZiUI+n0k+P7uuszOgZVzT9BsDx0xe9F1GD8dKF5TS2W q6FhHOg1zydGQMTk53KhOSlP+M+v1hZHLqZHeb6AepHNp83bYqZhjETap8pOEzaN qbtvmDnhhRqFmsL2DfwlUemB9R37t3JTX5e830MGwiXlM1xdiF1uBO3yojIGsO2N O52Y5Wdefl4thzjpK/XSRc/M7jwPQBXsvS+It7TWI50KZgh44QZjTuuOphzaQrCk 78CPQHSLOHyQoY9ZHW/paAD7G4OKsLA= =7LZY -END PGP SIGNATURE- attachment: lists.vcf___ For more information about ZODB, see http://zodb.org/ ZODB-Dev mailing list - ZODB-Dev@zope.org https://mail.zope.org/mailman/listinfo/zodb-dev
