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| | select() calls are used to poll sockets for activity (read, write and exceptions), and I suspect the issue was that the timeout value (which is specified as part of select()'s parameters) was set too high judging from the overall content; Web servers and clients alike would suffer considerable latency as a result of waiting too long for I/O ports to activate. Thus it's likely the Apache install was misconfigured somehow, since the default settings should be sufficient for most purposes (in my limited experience since I work solely with nginx these days). | | select() calls are used to poll sockets for activity (read, write and exceptions), and I suspect the issue was that the timeout value (which is specified as part of select()'s parameters) was set too high judging from the overall content; Web servers and clients alike would suffer considerable latency as a result of waiting too long for I/O ports to activate. Thus it's likely the Apache install was misconfigured somehow, since the default settings should be sufficient for most purposes (in my limited experience since I work solely with nginx these days). |
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| − | I had this problem writing a server in PHP, and it took a while to get PHP (under Win32) to stop hogging my precious CPU cycles by successful application of nonblocking sockets and a short timeout parameter. [[User:Thokling|Thokling]] ([[User talk:Thokling|talk]]) 15:24, 20 September 2013 (UTC) | + | I had this problem writing a server in PHP, and it took a while to get PHP (under Win32) to stop hogging my precious CPU cycles by successful application of nonblocking sockets and a short timeout parameter. *flex* [[User:Thokling|Thokling]] ([[User talk:Thokling|talk]]) 15:21, 20 September 2013 (UTC) |
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| − | :You are correct and I have modified the explanation. It could also be due to a loop polling a socket that will never be freed(a deadlock), this was my interpretation. [[Special:Contributions/108.162.246.117|108.162.246.117]] 07:05, 1 November 2013 (UTC)
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| − | The explanations above don't seem to match "the load climbing out of control". The load typically means the CPU load, not latency. If the server is stuck on reading from a socket, the latency will grow but the load will plunge, since it's _waiting_ and thus not consuming the CPU cycles. Two typical problems connected with select() are: (1) As the number of sockets polled grows, the overhead of select() grows, so it uses more and more CPU just to go through all the sockets and check them all for readiness. (2) If some socket reports readiness through select() and then the program does not handle that readiness but keeps including this socket into the following select() calls, it will be stuck in a tight loop retrying select() and using all the available CPU of one processor. A less extreme variety of this case is the program being notified of multiple sockets being ready but handling only one socket before repeating select(). In this case the program will continue making progress but with the increased overhead of the unnecessary select() calls. [[Special:Contributions/108.162.246.5|108.162.246.5]] 21:07, 30 January 2014 (UTC)
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| − | The start of the explanation refers to "black hat hackers" which doesn't seem relevant to the comic. I would have guessed that it relates to Red Hat, the company that sells and supports an enterprise Linux distribution (but becomes "Black Hat" because it is drawn in black and white). {{unsigned ip|108.162.208.155}}
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| − | What about the sideways reference to "hang" in the title-text? Shouldn't _something_ be said about that in the explanation? [[Special:Contributions/173.245.54.190|173.245.54.190]] 18:18, 28 August 2014 (UTC)
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| − | Looks about like what I'd expect of the BoFH. Except more helpfull and fewer dead bodies. [[Special:Contributions/108.162.216.112|108.162.216.112]] 17:45, 5 October 2014 (UTC)
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| − | Is it just me, or is this the only comic where Black Hat is named? [[User:Jacky720|Jacky720]] ([[User talk:Jacky720|talk]]) 16:41, 18 November 2016 (UTC)
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| − | I think the title may be pun with one aspect referring to the actual technical cause of the callers problems (as has been discussed/debated here, so I won't dwell on it) but also suggests that Black Hat only trolls "select calls". This is in keeping with some of his other antics, like sending Bobcats to 1 in 30 E-bay buyers in order to keep his seller score to 97% in the title text of: https://xkcd.com/325/ [[Special:Contributions/162.158.69.71|162.158.69.71]] 19:08, 7 October 2017 (UTC) Sam
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| − | The existence of a Black Hat support line for Linux may be a play on Red Hat Linux. --[[User:"The" Argus Panoptes|"The" Argus Panoptes]] ([[User talk:"The" Argus Panoptes|talk]]) 13:29, 1 September 2021 (UTC)
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