| … | |
… | |
| 2061 | longer exceeded. |
2061 | longer exceeded. |
| 2062 | |
2062 | |
| 2063 | In other words, this setting does not enforce a queue limit, but can be |
2063 | In other words, this setting does not enforce a queue limit, but can be |
| 2064 | used to make poll functions block if the limit is exceeded. |
2064 | used to make poll functions block if the limit is exceeded. |
| 2065 | |
2065 | |
| 2066 | This is a very bad function to use in interactive programs because it |
2066 | This is a bad function to use in interactive programs because it blocks, |
| 2067 | blocks, and a bad way to reduce concurrency because it is inexact: Better |
2067 | and a bad way to reduce concurrency because it is inexact. If you need to |
|
|
2068 | issue many requests without being able to call a poll function on demand, |
| 2068 | use an C<aio_group> together with a feed callback. |
2069 | it is better to use an C<aio_group> together with a feed callback. |
| 2069 | |
2070 | |
| 2070 | Its main use is in scripts without an event loop - when you want to stat |
2071 | Its main use is in scripts without an event loop - when you want to stat a |
| 2071 | a lot of files, you can write something like this: |
2072 | lot of files, you can write something like this: |
| 2072 | |
2073 | |
| 2073 | IO::AIO::max_outstanding 32; |
2074 | IO::AIO::max_outstanding 32; |
| 2074 | |
2075 | |
| 2075 | for my $path (...) { |
2076 | for my $path (...) { |
| 2076 | aio_stat $path , ...; |
2077 | aio_stat $path , ...; |
| 2077 | IO::AIO::poll_cb; |
2078 | IO::AIO::poll_cb; |
| 2078 | } |
2079 | } |
| 2079 | |
2080 | |
| 2080 | IO::AIO::flush; |
2081 | IO::AIO::flush; |
| 2081 | |
2082 | |
| 2082 | The call to C<poll_cb> inside the loop will normally return instantly, but |
2083 | The call to C<poll_cb> inside the loop will normally return instantly, |
| 2083 | as soon as more thna C<32> reqeusts are in-flight, it will block until |
2084 | allowing the loop to progress, but as soon as more than C<32> requests |
| 2084 | some requests have been handled. This keeps the loop from pushing a large |
2085 | are in-flight, it will block until some requests have been handled. This |
| 2085 | number of C<aio_stat> requests onto the queue. |
2086 | keeps the loop from pushing a large number of C<aio_stat> requests onto |
|
|
2087 | the queue (which, with many paths to stat, can use up a lot of memory). |
| 2086 | |
2088 | |
| 2087 | The default value for C<max_outstanding> is very large, so there is no |
2089 | The default value for C<max_outstanding> is very large, so there is no |
| 2088 | practical limit on the number of outstanding requests. |
2090 | practical limit on the number of outstanding requests. |
| 2089 | |
2091 | |
| 2090 | =back |
2092 | =back |
