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Diffstat (limited to '_posts/2013-4-9-erlang-tcp-socket-pull-pattern.md')
| -rw-r--r-- | _posts/2013-4-9-erlang-tcp-socket-pull-pattern.md | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/_posts/2013-4-9-erlang-tcp-socket-pull-pattern.md b/_posts/2013-4-9-erlang-tcp-socket-pull-pattern.md index 3f42b49..3e5f0af 100644 --- a/_posts/2013-4-9-erlang-tcp-socket-pull-pattern.md +++ b/_posts/2013-4-9-erlang-tcp-socket-pull-pattern.md @@ -1,5 +1,7 @@ --- title: "Erlang, tcp sockets, and active true" +description: >- + Using `{active:once}` isn't always the best way to handle connections. --- If you don't know erlang then [you're missing out][0]. If you do know erlang, @@ -9,7 +11,7 @@ number of active connections is desired. Each thread can autonomously handle its single client, greatly simplifying the logic of the whole application while still retaining [great performance characteristics][1]. -# Background +## Background For an erlang thread which owns a single socket there are three different ways to receive data off of that socket. These all revolve around the `active` @@ -30,7 +32,7 @@ to receive data off of that socket. These all revolve around the `active` read from using [recv/2][3] or be put in `{active,once}` or `{active,true}`. -# Which to use? +## Which to use? Many (most?) tutorials advocate using `{active,once}` in your application \[0]\[1]\[2]. This has to do with usability and security. When in `{active,true}` @@ -41,7 +43,7 @@ well as other messages from other erlang processes at the same time you can't use `{active,false}`. So `{active,once}` is generally preferred because it deals with both of these problems quite well. -# Why not to use `{active,once}` +## Why not to use `{active,once}` Here's what your classic `{active,once}` enabled tcp socket implementation will probably look like: @@ -229,7 +231,7 @@ This time our process spent almost no time at all (according to eprof, 0%) fiddling with the socket opts. Instead it spent all of its time in the read_loop doing the work we actually want to be doing. -# So what does this mean? +## So what does this mean? I'm by no means advocating never using `{active,once}`. The security concern is still a completely valid concern and one that `{active,once}` mitigates quite @@ -238,7 +240,7 @@ performance implications which have the potential to bite you if you're not careful, especially in cases where a socket is going to be receiving a large amount of traffic. -# Meta +## Meta These tests were done using R15B03, but I've done similar ones in R14 and found similar results. I have not tested R16. |