Skip to content

Use GC.AllocateUninitializedArray in File.ReadAllBytes[Async] #132398

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
adamsitnik merged 1 commit into from
Aug 17, 2026
+6 −2
Merged

Use GC.AllocateUninitializedArray in File.ReadAllBytes[Async] #132398

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
8 changes: 6 additions & 2 deletions src/libraries/System.Private.CoreLib/src/System/IO/File.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -742,7 +742,9 @@ public static byte[] ReadAllBytes(string path)

int index = 0;
int count = (int)fileLength;
byte[] bytes = new byte[count];
// The entire array is overwritten by the read loop below (an exception is thrown
// if the file is truncated before all the bytes are read), so it does not need to be zeroed.
byte[] bytes = GC.AllocateUninitializedArray<byte>(count);
Comment thread
adamsitnik marked this conversation as resolved.
while (count > 0)
{
int n = RandomAccess.ReadAtOffset(sfh, bytes.AsSpan(index, count), index);
Expand Down Expand Up @@ -1225,7 +1227,9 @@ private static async Task<byte[]> InternalReadAllBytesAsync(SafeFileHandle sfh,
using (sfh)
{
int index = 0;
byte[] bytes = new byte[count];
// The entire array is overwritten by the read loop below (an exception is thrown
// if the file is truncated before all the bytes are read), so it does not need to be zeroed.
byte[] bytes = GC.AllocateUninitializedArray<byte>(count);
do
{
int n = await RandomAccess.ReadAtOffsetAsync(sfh, bytes.AsMemory(index), index, cancellationToken).ConfigureAwait(false);
Expand Down
Loading