OpenRead asynchronously
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I'm using the following C# code to read a tiny text file over a network share:
string fileContent;
using (var stream = File.OpenRead(filePath))
using (var reader = new StreamReader(stream, FileEncoding))
{
fileContent = await reader.ReadToEndAsync();
}
Even though the text file is very small (less than 10 KB) this operation sometimes takes ~7 seconds to run. When that happens, I've noticed most of the time is spent on
File.OpenRead(filePath)
This is probably due to Windows having to resolve the file share and to acquire locks on the file over the network. As that method call is not asynchronous, this is blocking my current thread for several seconds.
Is there a safe way to read a file from disk asynchronously that also performs OpenRead asynchronously?
c# file-io async-await
edited Apr 2 '15 at 11:03
svick
177k40298417
asked Apr 2 '15 at 1:32
roimroim
2,21621727
add a comment |
I'm using the following C# code to read a tiny text file over a network share:
string fileContent;
using (var stream = File.OpenRead(filePath))
using (var reader = new StreamReader(stream, FileEncoding))
{
fileContent = await reader.ReadToEndAsync();
}
Even though the text file is very small (less than 10 KB) this operation sometimes takes ~7 seconds to run. When that happens, I've noticed most of the time is spent on
File.OpenRead(filePath)
This is probably due to Windows having to resolve the file share and to acquire locks on the file over the network. As that method call is not asynchronous, this is blocking my current thread for several seconds.
Is there a safe way to read a file from disk asynchronously that also performs OpenRead asynchronously?
c# file-io async-await
edited Apr 2 '15 at 11:03
svick
177k40298417
asked Apr 2 '15 at 1:32
roimroim
2,21621727
Have you tried copying or moving the file to local first and then reading it? Just try it if you haven't already to test it, that may show some other possible problem in network if that is the case.
– Oğuz Sezer
Apr 2 '15 at 11:09
add a comment |
I'm using the following C# code to read a tiny text file over a network share:
string fileContent;
using (var stream = File.OpenRead(filePath))
using (var reader = new StreamReader(stream, FileEncoding))
{
fileContent = await reader.ReadToEndAsync();
}
Even though the text file is very small (less than 10 KB) this operation sometimes takes ~7 seconds to run. When that happens, I've noticed most of the time is spent on
File.OpenRead(filePath)
This is probably due to Windows having to resolve the file share and to acquire locks on the file over the network. As that method call is not asynchronous, this is blocking my current thread for several seconds.
Is there a safe way to read a file from disk asynchronously that also performs OpenRead asynchronously?
c# file-io async-await
edited Apr 2 '15 at 11:03
svick
177k40298417
asked Apr 2 '15 at 1:32
roimroim
2,21621727
I'm using the following C# code to read a tiny text file over a network share:
string fileContent;
using (var stream = File.OpenRead(filePath))
using (var reader = new StreamReader(stream, FileEncoding))
{
fileContent = await reader.ReadToEndAsync();
}
Even though the text file is very small (less than 10 KB) this operation sometimes takes ~7 seconds to run. When that happens, I've noticed most of the time is spent on
File.OpenRead(filePath)
This is probably due to Windows having to resolve the file share and to acquire locks on the file over the network. As that method call is not asynchronous, this is blocking my current thread for several seconds.
Is there a safe way to read a file from disk asynchronously that also performs OpenRead asynchronously?
c# file-io async-await
c# file-io async-await
edited Apr 2 '15 at 11:03
svick
177k40298417
asked Apr 2 '15 at 1:32
roimroim
2,21621727
edited Apr 2 '15 at 11:03
svick
177k40298417
asked Apr 2 '15 at 1:32
roimroim
2,21621727
edited Apr 2 '15 at 11:03
svick
177k40298417
edited Apr 2 '15 at 11:03
svick
177k40298417
edited Apr 2 '15 at 11:03
svick
177k40298417
177k40298417
asked Apr 2 '15 at 1:32
roimroim
2,21621727
asked Apr 2 '15 at 1:32
roimroim
2,21621727
asked Apr 2 '15 at 1:32
roimroim
2,21621727
2,21621727
Have you tried copying or moving the file to local first and then reading it? Just try it if you haven't already to test it, that may show some other possible problem in network if that is the case.
– Oğuz Sezer
Apr 2 '15 at 11:09
add a comment |
Have you tried copying or moving the file to local first and then reading it? Just try it if you haven't already to test it, that may show some other possible problem in network if that is the case.
– Oğuz Sezer
Apr 2 '15 at 11:09
Have you tried copying or moving the file to local first and then reading it? Just try it if you haven't already to test it, that may show some other possible problem in network if that is the case.
– Oğuz Sezer
Apr 2 '15 at 11:09
Have you tried copying or moving the file to local first and then reading it? Just try it if you haven't already to test it, that may show some other possible problem in network if that is the case.
– Oğuz Sezer
Apr 2 '15 at 11:09
add a comment |
1 Answer
1
active
oldest
votes
No, unfortunately this is missing in the Win32 API. Device drivers do have the notion of an "asynchronous open", so the infrastructure is there; but the Win32 API does not expose this functionality.
Naturally, this means that .NET can't expose that functionality, either. You can, however, use a "fake asynchronous" operation - i.e., wrap your file read within a Task.Run, so that your UI thread isn't blocked. However, if you're on ASP.NET, then don't use Task.Run; just keep the (blocking) file open as it is.
answered Apr 2 '15 at 1:47
Stephen ClearyStephen Cleary
290k49485608
HOLY CRAP. Is there a voice to get that added to the Win 10 API?
– Aron
Apr 2 '15 at 1:50
I'm not on ASP.NET, but I would be interested in knowing why that would be a bad choice there specifically. Any references?
– roim
Apr 2 '15 at 3:31
@aron: Not to my knowledge; feel free to open a UserVoice issue. I believe that async close is also possible, but may be more difficult to model.
– Stephen Cleary
Apr 2 '15 at 10:10
@roim: The main goal ofasyncon a client UI is to free up the UI thread so the app is more responsive; it's acceptable (but not ideal) to useTask.Run, which just blocks a thread pool thread so the UI thread is not blocked.
– Stephen Cleary
Apr 2 '15 at 10:12
4
@roim: The main goal ofasyncon ASP.NET is to free up thread pool threads so the server can scale; usingTask.Run, would force a context switch and then use up one thread pool thread to free up another thread pool thread. A net loss. I've written about it a bit in an MSDN article and on my blog.
– Stephen Cleary
Apr 2 '15 at 10:15
|
show 1 more comment
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
No, unfortunately this is missing in the Win32 API. Device drivers do have the notion of an "asynchronous open", so the infrastructure is there; but the Win32 API does not expose this functionality.
Naturally, this means that .NET can't expose that functionality, either. You can, however, use a "fake asynchronous" operation - i.e., wrap your file read within a Task.Run, so that your UI thread isn't blocked. However, if you're on ASP.NET, then don't use Task.Run; just keep the (blocking) file open as it is.
answered Apr 2 '15 at 1:47
Stephen ClearyStephen Cleary
290k49485608
HOLY CRAP. Is there a voice to get that added to the Win 10 API?
– Aron
Apr 2 '15 at 1:50
I'm not on ASP.NET, but I would be interested in knowing why that would be a bad choice there specifically. Any references?
– roim
Apr 2 '15 at 3:31
@aron: Not to my knowledge; feel free to open a UserVoice issue. I believe that async close is also possible, but may be more difficult to model.
– Stephen Cleary
Apr 2 '15 at 10:10
@roim: The main goal ofasyncon a client UI is to free up the UI thread so the app is more responsive; it's acceptable (but not ideal) to useTask.Run, which just blocks a thread pool thread so the UI thread is not blocked.
– Stephen Cleary
Apr 2 '15 at 10:12
4
@roim: The main goal ofasyncon ASP.NET is to free up thread pool threads so the server can scale; usingTask.Run, would force a context switch and then use up one thread pool thread to free up another thread pool thread. A net loss. I've written about it a bit in an MSDN article and on my blog.
– Stephen Cleary
Apr 2 '15 at 10:15
|
show 1 more comment
No, unfortunately this is missing in the Win32 API. Device drivers do have the notion of an "asynchronous open", so the infrastructure is there; but the Win32 API does not expose this functionality.
Naturally, this means that .NET can't expose that functionality, either. You can, however, use a "fake asynchronous" operation - i.e., wrap your file read within a Task.Run, so that your UI thread isn't blocked. However, if you're on ASP.NET, then don't use Task.Run; just keep the (blocking) file open as it is.
answered Apr 2 '15 at 1:47
Stephen ClearyStephen Cleary
290k49485608
HOLY CRAP. Is there a voice to get that added to the Win 10 API?
– Aron
Apr 2 '15 at 1:50
I'm not on ASP.NET, but I would be interested in knowing why that would be a bad choice there specifically. Any references?
– roim
Apr 2 '15 at 3:31
@aron: Not to my knowledge; feel free to open a UserVoice issue. I believe that async close is also possible, but may be more difficult to model.
– Stephen Cleary
Apr 2 '15 at 10:10
@roim: The main goal ofasyncon a client UI is to free up the UI thread so the app is more responsive; it's acceptable (but not ideal) to useTask.Run, which just blocks a thread pool thread so the UI thread is not blocked.
– Stephen Cleary
Apr 2 '15 at 10:12
4
@roim: The main goal ofasyncon ASP.NET is to free up thread pool threads so the server can scale; usingTask.Run, would force a context switch and then use up one thread pool thread to free up another thread pool thread. A net loss. I've written about it a bit in an MSDN article and on my blog.
– Stephen Cleary
Apr 2 '15 at 10:15
|
show 1 more comment
No, unfortunately this is missing in the Win32 API. Device drivers do have the notion of an "asynchronous open", so the infrastructure is there; but the Win32 API does not expose this functionality.
Naturally, this means that .NET can't expose that functionality, either. You can, however, use a "fake asynchronous" operation - i.e., wrap your file read within a Task.Run, so that your UI thread isn't blocked. However, if you're on ASP.NET, then don't use Task.Run; just keep the (blocking) file open as it is.
answered Apr 2 '15 at 1:47
Stephen ClearyStephen Cleary
290k49485608
No, unfortunately this is missing in the Win32 API. Device drivers do have the notion of an "asynchronous open", so the infrastructure is there; but the Win32 API does not expose this functionality.
Naturally, this means that .NET can't expose that functionality, either. You can, however, use a "fake asynchronous" operation - i.e., wrap your file read within a Task.Run, so that your UI thread isn't blocked. However, if you're on ASP.NET, then don't use Task.Run; just keep the (blocking) file open as it is.
answered Apr 2 '15 at 1:47
Stephen ClearyStephen Cleary
290k49485608
answered Apr 2 '15 at 1:47
Stephen ClearyStephen Cleary
290k49485608
answered Apr 2 '15 at 1:47
Stephen ClearyStephen Cleary
290k49485608
answered Apr 2 '15 at 1:47
Stephen ClearyStephen Cleary
290k49485608
290k49485608
HOLY CRAP. Is there a voice to get that added to the Win 10 API?
– Aron
Apr 2 '15 at 1:50
I'm not on ASP.NET, but I would be interested in knowing why that would be a bad choice there specifically. Any references?
– roim
Apr 2 '15 at 3:31
@aron: Not to my knowledge; feel free to open a UserVoice issue. I believe that async close is also possible, but may be more difficult to model.
– Stephen Cleary
Apr 2 '15 at 10:10
@roim: The main goal ofasyncon a client UI is to free up the UI thread so the app is more responsive; it's acceptable (but not ideal) to useTask.Run, which just blocks a thread pool thread so the UI thread is not blocked.
– Stephen Cleary
Apr 2 '15 at 10:12
4
@roim: The main goal ofasyncon ASP.NET is to free up thread pool threads so the server can scale; usingTask.Run, would force a context switch and then use up one thread pool thread to free up another thread pool thread. A net loss. I've written about it a bit in an MSDN article and on my blog.
– Stephen Cleary
Apr 2 '15 at 10:15
|
show 1 more comment
HOLY CRAP. Is there a voice to get that added to the Win 10 API?
– Aron
Apr 2 '15 at 1:50
I'm not on ASP.NET, but I would be interested in knowing why that would be a bad choice there specifically. Any references?
– roim
Apr 2 '15 at 3:31
@aron: Not to my knowledge; feel free to open a UserVoice issue. I believe that async close is also possible, but may be more difficult to model.
– Stephen Cleary
Apr 2 '15 at 10:10
@roim: The main goal ofasyncon a client UI is to free up the UI thread so the app is more responsive; it's acceptable (but not ideal) to useTask.Run, which just blocks a thread pool thread so the UI thread is not blocked.
– Stephen Cleary
Apr 2 '15 at 10:12
4
@roim: The main goal ofasyncon ASP.NET is to free up thread pool threads so the server can scale; usingTask.Run, would force a context switch and then use up one thread pool thread to free up another thread pool thread. A net loss. I've written about it a bit in an MSDN article and on my blog.
– Stephen Cleary
Apr 2 '15 at 10:15
HOLY CRAP. Is there a voice to get that added to the Win 10 API?
– Aron
Apr 2 '15 at 1:50
HOLY CRAP. Is there a voice to get that added to the Win 10 API?
– Aron
Apr 2 '15 at 1:50
I'm not on ASP.NET, but I would be interested in knowing why that would be a bad choice there specifically. Any references?
– roim
Apr 2 '15 at 3:31
I'm not on ASP.NET, but I would be interested in knowing why that would be a bad choice there specifically. Any references?
– roim
Apr 2 '15 at 3:31
@aron: Not to my knowledge; feel free to open a UserVoice issue. I believe that async close is also possible, but may be more difficult to model.
– Stephen Cleary
Apr 2 '15 at 10:10
@aron: Not to my knowledge; feel free to open a UserVoice issue. I believe that async close is also possible, but may be more difficult to model.
– Stephen Cleary
Apr 2 '15 at 10:10
@roim: The main goal of
async on a client UI is to free up the UI thread so the app is more responsive; it's acceptable (but not ideal) to use Task.Run, which just blocks a thread pool thread so the UI thread is not blocked.– Stephen Cleary
Apr 2 '15 at 10:12
@roim: The main goal of
async on a client UI is to free up the UI thread so the app is more responsive; it's acceptable (but not ideal) to use Task.Run, which just blocks a thread pool thread so the UI thread is not blocked.– Stephen Cleary
Apr 2 '15 at 10:12
4
4
@roim: The main goal of
async on ASP.NET is to free up thread pool threads so the server can scale; using Task.Run, would force a context switch and then use up one thread pool thread to free up another thread pool thread. A net loss. I've written about it a bit in an MSDN article and on my blog.– Stephen Cleary
Apr 2 '15 at 10:15
@roim: The main goal of
async on ASP.NET is to free up thread pool threads so the server can scale; using Task.Run, would force a context switch and then use up one thread pool thread to free up another thread pool thread. A net loss. I've written about it a bit in an MSDN article and on my blog.– Stephen Cleary
Apr 2 '15 at 10:15
|
show 1 more comment
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Have you tried copying or moving the file to local first and then reading it? Just try it if you haven't already to test it, that may show some other possible problem in network if that is the case.
– Oğuz Sezer
Apr 2 '15 at 11:09