Are fts_read and fts_children not thread safe?
This answer recommends fts as a good way to have a reentrant filesystem traversal. While reading the manpages, however, I noticed that fts_read and fts_children are marked as MT-Unsafe.
I could not find anywhere information on why it was marked as such. I found this thread, so I suspect the reason is because of chdir being called (two threads will try to chdir the process at the same time, it can't be good).
If that is so, I guess that passing FTS_NOCHDIR would be enough to have thread safety. Is there any other reason I don't see?
(And for the record, I'm very surprised that we came to this day without having a good reentrant, reasonable to use way of scanning through a filesystem tree! Seriously? ☺)
c linux bsd
asked Nov 24 '18 at 17:28
DacavDacav
7,12144569
add a comment |
This answer recommends fts as a good way to have a reentrant filesystem traversal. While reading the manpages, however, I noticed that fts_read and fts_children are marked as MT-Unsafe.
I could not find anywhere information on why it was marked as such. I found this thread, so I suspect the reason is because of chdir being called (two threads will try to chdir the process at the same time, it can't be good).
If that is so, I guess that passing FTS_NOCHDIR would be enough to have thread safety. Is there any other reason I don't see?
(And for the record, I'm very surprised that we came to this day without having a good reentrant, reasonable to use way of scanning through a filesystem tree! Seriously? ☺)
c linux bsd
asked Nov 24 '18 at 17:28
DacavDacav
7,12144569
Regarding how we came to this day without havign a reentrant way to scan the filesystem: it is by definition an IO-bound task, so there's likely not going to be much gain from doing it in parallel. All your threads will just end up waiting for the same physical medium anyway so why bother?
– Britton Kerin
Nov 24 '18 at 22:22
@BrittonKerin - In a single-threaded program there are also signals and other sources of interruption. Also reentrant code fosters better quality in general, even outside the scope of multi-threaded programming. Quality matters :)
– Dacav
Nov 26 '18 at 7:11
add a comment |
This answer recommends fts as a good way to have a reentrant filesystem traversal. While reading the manpages, however, I noticed that fts_read and fts_children are marked as MT-Unsafe.
I could not find anywhere information on why it was marked as such. I found this thread, so I suspect the reason is because of chdir being called (two threads will try to chdir the process at the same time, it can't be good).
If that is so, I guess that passing FTS_NOCHDIR would be enough to have thread safety. Is there any other reason I don't see?
(And for the record, I'm very surprised that we came to this day without having a good reentrant, reasonable to use way of scanning through a filesystem tree! Seriously? ☺)
c linux bsd
asked Nov 24 '18 at 17:28
DacavDacav
7,12144569
This answer recommends fts as a good way to have a reentrant filesystem traversal. While reading the manpages, however, I noticed that fts_read and fts_children are marked as MT-Unsafe.
I could not find anywhere information on why it was marked as such. I found this thread, so I suspect the reason is because of chdir being called (two threads will try to chdir the process at the same time, it can't be good).
If that is so, I guess that passing FTS_NOCHDIR would be enough to have thread safety. Is there any other reason I don't see?
(And for the record, I'm very surprised that we came to this day without having a good reentrant, reasonable to use way of scanning through a filesystem tree! Seriously? ☺)
c linux bsd
c linux bsd
asked Nov 24 '18 at 17:28
DacavDacav
7,12144569
asked Nov 24 '18 at 17:28
DacavDacav
7,12144569
edited Nov 24 '18 at 17:38
Dacav
asked Nov 24 '18 at 17:28
DacavDacav
7,12144569
asked Nov 24 '18 at 17:28
DacavDacav
7,12144569
asked Nov 24 '18 at 17:28
DacavDacav
7,12144569
7,12144569
Regarding how we came to this day without havign a reentrant way to scan the filesystem: it is by definition an IO-bound task, so there's likely not going to be much gain from doing it in parallel. All your threads will just end up waiting for the same physical medium anyway so why bother?
– Britton Kerin
Nov 24 '18 at 22:22
@BrittonKerin - In a single-threaded program there are also signals and other sources of interruption. Also reentrant code fosters better quality in general, even outside the scope of multi-threaded programming. Quality matters :)
– Dacav
Nov 26 '18 at 7:11
add a comment |
Regarding how we came to this day without havign a reentrant way to scan the filesystem: it is by definition an IO-bound task, so there's likely not going to be much gain from doing it in parallel. All your threads will just end up waiting for the same physical medium anyway so why bother?
– Britton Kerin
Nov 24 '18 at 22:22
@BrittonKerin - In a single-threaded program there are also signals and other sources of interruption. Also reentrant code fosters better quality in general, even outside the scope of multi-threaded programming. Quality matters :)
– Dacav
Nov 26 '18 at 7:11
Regarding how we came to this day without havign a reentrant way to scan the filesystem: it is by definition an IO-bound task, so there's likely not going to be much gain from doing it in parallel. All your threads will just end up waiting for the same physical medium anyway so why bother?
– Britton Kerin
Nov 24 '18 at 22:22
Regarding how we came to this day without havign a reentrant way to scan the filesystem: it is by definition an IO-bound task, so there's likely not going to be much gain from doing it in parallel. All your threads will just end up waiting for the same physical medium anyway so why bother?
– Britton Kerin
Nov 24 '18 at 22:22
@BrittonKerin - In a single-threaded program there are also signals and other sources of interruption. Also reentrant code fosters better quality in general, even outside the scope of multi-threaded programming. Quality matters :)
– Dacav
Nov 26 '18 at 7:11
@BrittonKerin - In a single-threaded program there are also signals and other sources of interruption. Also reentrant code fosters better quality in general, even outside the scope of multi-threaded programming. Quality matters :)
– Dacav
Nov 26 '18 at 7:11
add a comment |
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Regarding how we came to this day without havign a reentrant way to scan the filesystem: it is by definition an IO-bound task, so there's likely not going to be much gain from doing it in parallel. All your threads will just end up waiting for the same physical medium anyway so why bother?
– Britton Kerin
Nov 24 '18 at 22:22
@BrittonKerin - In a single-threaded program there are also signals and other sources of interruption. Also reentrant code fosters better quality in general, even outside the scope of multi-threaded programming. Quality matters :)
– Dacav
Nov 26 '18 at 7:11