r352079 - [FileManager] Revert r347205 to avoid PCH file-descriptor leak.
Hans Wennborg via cfe-commits
cfe-commits at lists.llvm.org
Mon Jan 28 05:32:24 PST 2019
Thanks for looking into this. I've reverted the test assertions on the
branch in r352354.
On Mon, Jan 28, 2019 at 1:14 AM Sam McCall <sam.mccall at gmail.com> wrote:
>
> This is kind of expected: r347205 was a bugfix.
> Reverting it causes a real bug, and the tests are failing. The bug is acceptable for 8.0 - it affects only a marginal case (go-to-definition on a #include *outside* the preamble section of a file that was also transitively #included in the preamble).
>
> One mystery: why are the tests failing on the branch but not on trunk?
> I do want to dig into this today/tomorrow, but I don't think it affects what we do on the branch.
>
> The right fix for the branch is just to delete the three failing assertions (for locations 5, 6, 7 in that test).
> Is it possible to do this directly on the branch (without deleting them on trunk)?
>
> On Sat, Jan 26, 2019 at 1:30 AM Hans Wennborg <hans at chromium.org> wrote:
>>
>> Sorry to bring more bad news, but merging this seems to have regressed
>> a clangd test on the branch (I didn't notice at the time, because I
>> ran the wrong set of tests, d'oh).
>>
>> I've searched my inbox but couldn't find any recent commits touching
>> the test. Do you have any idea what might be happening?
>>
>> ******************** TEST 'Extra Tools Unit Tests ::
>> clangd/./ClangdTests/GoToInclude.All' FAILED ********************
>> Note: Google Test filter = GoToInclude.All
>> [==========] Running 1 test from 1 test case.
>> [----------] Global test environment set-up.
>> [----------] 1 test from GoToInclude
>> [ RUN ] GoToInclude.All
>> /work/llvm-8/llvm/tools/clang/tools/extra/unittests/clangd/XRefsTests.cpp:1086:
>> Failure
>> Value of: *Locations
>> Expected: has 1 element that file range ("/clangd-test/foo.h", 0:0-0:0)
>> Actual: {}
>> /work/llvm-8/llvm/tools/clang/tools/extra/unittests/clangd/XRefsTests.cpp:1096:
>> Failure
>> Value of: *Locations
>> Expected: has 1 element that file range ("/clangd-test/foo.h", 0:0-0:0)
>> Actual: {}
>> /work/llvm-8/llvm/tools/clang/tools/extra/unittests/clangd/XRefsTests.cpp:1101:
>> Failure
>> Value of: *Locations
>> Expected: has 1 element that file range ("/clangd-test/foo.h", 0:0-0:0)
>> Actual: {}
>> [ FAILED ] GoToInclude.All (14 ms)
>> [----------] 1 test from GoToInclude (14 ms total)
>>
>> [----------] Global test environment tear-down
>> [==========] 1 test from 1 test case ran. (14 ms total)
>> [ PASSED ] 0 tests.
>> [ FAILED ] 1 test, listed below:
>> [ FAILED ] GoToInclude.All
>>
>> 1 FAILED TEST
>> Updating file /clangd-test/foo.h with command [/clangd-test] clang
>> -ffreestanding /clangd-test/foo.h
>> Updating file /clangd-test/foo.cpp with command [/clangd-test] clang
>> -ffreestanding /clangd-test/foo.cpp
>> Preamble for file /clangd-test/foo.h cannot be reused. Attempting to rebuild it.
>> Preamble for file /clangd-test/foo.cpp cannot be reused. Attempting to
>> rebuild it.
>> Built preamble of size 169108 for file /clangd-test/foo.h
>> Built preamble of size 173056 for file /clangd-test/foo.cpp
>>
>> ********************
>> Testing Time: 5.30s
>> ********************
>> Failing Tests (1):
>> Extra Tools Unit Tests :: clangd/./ClangdTests/GoToInclude.All
>>
>> Expected Passes : 1123
>> Expected Failures : 1
>> Unsupported Tests : 3
>> Unexpected Failures: 1
>>
>> On Fri, Jan 25, 2019 at 10:18 AM Hans Wennborg <hans at chromium.org> wrote:
>> >
>> > Merged to 8.0 in r352225.
>> >
>> > On Thu, Jan 24, 2019 at 10:55 AM Sam McCall via cfe-commits
>> > <cfe-commits at lists.llvm.org> wrote:
>> > >
>> > > Author: sammccall
>> > > Date: Thu Jan 24 10:55:24 2019
>> > > New Revision: 352079
>> > >
>> > > URL: http://llvm.org/viewvc/llvm-project?rev=352079&view=rev
>> > > Log:
>> > > [FileManager] Revert r347205 to avoid PCH file-descriptor leak.
>> > >
>> > > Summary:
>> > > r347205 fixed a bug in FileManager: first calling
>> > > getFile(shouldOpen=false) and then getFile(shouldOpen=true) results in
>> > > the file not being open.
>> > >
>> > > Unfortunately, some code was (inadvertently?) relying on this bug: when
>> > > building with a PCH, the file entries are obtained first by passing
>> > > shouldOpen=false, and then later shouldOpen=true, without any intention
>> > > of reading them. After r347205, they do get unneccesarily opened.
>> > > Aside from extra operations, this means they need to be closed. Normally
>> > > files are closed when their contents are read. As these files are never
>> > > read, they stay open until clang exits. On platforms with a low
>> > > open-files limit (e.g. Mac), this can lead to spurious file-not-found
>> > > errors when building large projects with PCH enabled, e.g.
>> > > https://bugs.chromium.org/p/chromium/issues/detail?id=924225
>> > >
>> > > Fixing the callsites to pass shouldOpen=false when the file won't be
>> > > read is not quite trivial (that info isn't available at the direct
>> > > callsite), and passing shouldOpen=false is a performance regression (it
>> > > results in open+fstat pairs being replaced by stat+open).
>> > >
>> > > So an ideal fix is going to be a little risky and we need some fix soon
>> > > (especially for the llvm 8 branch).
>> > > The problem addressed by r347205 is rare and has only been observed in
>> > > clangd. It was present in llvm-7, so we can live with it for now.
>> > >
>> > > Reviewers: bkramer, thakis
>> > >
>> > > Subscribers: ilya-biryukov, ioeric, kadircet, cfe-commits
>> > >
>> > > Differential Revision: https://reviews.llvm.org/D57165
>> > >
>> > > Added:
>> > > cfe/trunk/test/PCH/leakfiles
>> > > Modified:
>> > > cfe/trunk/include/clang/Basic/FileManager.h
>> > > cfe/trunk/lib/Basic/FileManager.cpp
>> > > cfe/trunk/unittests/Basic/FileManagerTest.cpp
>> > >
>> > > Modified: cfe/trunk/include/clang/Basic/FileManager.h
>> > > URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/FileManager.h?rev=352079&r1=352078&r2=352079&view=diff
>> > > ==============================================================================
>> > > --- cfe/trunk/include/clang/Basic/FileManager.h (original)
>> > > +++ cfe/trunk/include/clang/Basic/FileManager.h Thu Jan 24 10:55:24 2019
>> > > @@ -69,15 +69,14 @@ class FileEntry {
>> > > bool IsNamedPipe;
>> > > bool InPCH;
>> > > bool IsValid; // Is this \c FileEntry initialized and valid?
>> > > - bool DeferredOpen; // Created by getFile(OpenFile=0); may open later.
>> > >
>> > > /// The open file, if it is owned by the \p FileEntry.
>> > > mutable std::unique_ptr<llvm::vfs::File> File;
>> > >
>> > > public:
>> > > FileEntry()
>> > > - : UniqueID(0, 0), IsNamedPipe(false), InPCH(false), IsValid(false),
>> > > - DeferredOpen(false) {}
>> > > + : UniqueID(0, 0), IsNamedPipe(false), InPCH(false), IsValid(false)
>> > > + {}
>> > >
>> > > FileEntry(const FileEntry &) = delete;
>> > > FileEntry &operator=(const FileEntry &) = delete;
>> > >
>> > > Modified: cfe/trunk/lib/Basic/FileManager.cpp
>> > > URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Basic/FileManager.cpp?rev=352079&r1=352078&r2=352079&view=diff
>> > > ==============================================================================
>> > > --- cfe/trunk/lib/Basic/FileManager.cpp (original)
>> > > +++ cfe/trunk/lib/Basic/FileManager.cpp Thu Jan 24 10:55:24 2019
>> > > @@ -188,21 +188,15 @@ const FileEntry *FileManager::getFile(St
>> > > *SeenFileEntries.insert(std::make_pair(Filename, nullptr)).first;
>> > >
>> > > // See if there is already an entry in the map.
>> > > - if (NamedFileEnt.second) {
>> > > - if (NamedFileEnt.second == NON_EXISTENT_FILE)
>> > > - return nullptr;
>> > > - // Entry exists: return it *unless* it wasn't opened and open is requested.
>> > > - if (!(NamedFileEnt.second->DeferredOpen && openFile))
>> > > - return NamedFileEnt.second;
>> > > - // We previously stat()ed the file, but didn't open it: do that below.
>> > > - // FIXME: the below does other redundant work too (stats the dir and file).
>> > > - } else {
>> > > - // By default, initialize it to invalid.
>> > > - NamedFileEnt.second = NON_EXISTENT_FILE;
>> > > - }
>> > > + if (NamedFileEnt.second)
>> > > + return NamedFileEnt.second == NON_EXISTENT_FILE ? nullptr
>> > > + : NamedFileEnt.second;
>> > >
>> > > ++NumFileCacheMisses;
>> > >
>> > > + // By default, initialize it to invalid.
>> > > + NamedFileEnt.second = NON_EXISTENT_FILE;
>> > > +
>> > > // Get the null-terminated file name as stored as the key of the
>> > > // SeenFileEntries map.
>> > > StringRef InterndFileName = NamedFileEnt.first();
>> > > @@ -240,7 +234,6 @@ const FileEntry *FileManager::getFile(St
>> > > // It exists. See if we have already opened a file with the same inode.
>> > > // This occurs when one dir is symlinked to another, for example.
>> > > FileEntry &UFE = UniqueRealFiles[Data.UniqueID];
>> > > - UFE.DeferredOpen = !openFile;
>> > >
>> > > NamedFileEnt.second = &UFE;
>> > >
>> > > @@ -257,15 +250,6 @@ const FileEntry *FileManager::getFile(St
>> > > InterndFileName = NamedFileEnt.first().data();
>> > > }
>> > >
>> > > - // If we opened the file for the first time, record the resulting info.
>> > > - // Do this even if the cache entry was valid, maybe we didn't previously open.
>> > > - if (F && !UFE.File) {
>> > > - if (auto PathName = F->getName())
>> > > - fillRealPathName(&UFE, *PathName);
>> > > - UFE.File = std::move(F);
>> > > - assert(!UFE.DeferredOpen && "we just opened it!");
>> > > - }
>> > > -
>> > > if (UFE.isValid()) { // Already have an entry with this inode, return it.
>> > >
>> > > // FIXME: this hack ensures that if we look up a file by a virtual path in
>> > > @@ -296,9 +280,13 @@ const FileEntry *FileManager::getFile(St
>> > > UFE.UniqueID = Data.UniqueID;
>> > > UFE.IsNamedPipe = Data.IsNamedPipe;
>> > > UFE.InPCH = Data.InPCH;
>> > > + UFE.File = std::move(F);
>> > > UFE.IsValid = true;
>> > > - // Note File and DeferredOpen were initialized above.
>> > >
>> > > + if (UFE.File) {
>> > > + if (auto PathName = UFE.File->getName())
>> > > + fillRealPathName(&UFE, *PathName);
>> > > + }
>> > > return &UFE;
>> > > }
>> > >
>> > > @@ -370,7 +358,6 @@ FileManager::getVirtualFile(StringRef Fi
>> > > UFE->UID = NextFileUID++;
>> > > UFE->IsValid = true;
>> > > UFE->File.reset();
>> > > - UFE->DeferredOpen = false;
>> > > return UFE;
>> > > }
>> > >
>> > >
>> > > Added: cfe/trunk/test/PCH/leakfiles
>> > > URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/PCH/leakfiles?rev=352079&view=auto
>> > > ==============================================================================
>> > > --- cfe/trunk/test/PCH/leakfiles (added)
>> > > +++ cfe/trunk/test/PCH/leakfiles Thu Jan 24 10:55:24 2019
>> > > @@ -0,0 +1,29 @@
>> > > +// Test that compiling using a PCH doesn't leak file descriptors.
>> > > +// https://bugs.chromium.org/p/chromium/issues/detail?id=924225
>> > > +//
>> > > +// This test requires bash loops and ulimit.
>> > > +// REQUIRES: shell
>> > > +// UNSUPPORTED: win32
>> > > +//
>> > > +// Set up source files. lib/lib.h includes lots of lib*.h files in that dir.
>> > > +// client.c includes lib/lib.h, and also the individual files directly.
>> > > +//
>> > > +// RUN: rm -rf %t
>> > > +// RUN: mkdir %t
>> > > +// RUN: cd %t
>> > > +// RUN: mkdir lib
>> > > +// RUN: for i in {1..300}; do touch lib/lib$i.h; done
>> > > +// RUN: for i in {1..300}; do echo "#include \"lib$i.h\"" >> lib/lib.h; done
>> > > +// RUN: echo "#include \"lib/lib.h\"" > client.c
>> > > +// RUN: for i in {1..300}; do echo "#include \"lib/lib$i.h\"" >> client.c; done
>> > > +//
>> > > +// We want to verify that we don't hold all the files open at the same time.
>> > > +// This is important e.g. on mac, which has a low default FD limit.
>> > > +// RUN: ulimit -n 100
>> > > +//
>> > > +// Test without PCH.
>> > > +// RUN: %clang_cc1 -fsyntax-only -Ilib/ client.c
>> > > +//
>> > > +// Test with PCH.
>> > > +// RUN: %clang_cc1 -emit-pch -o pch -Ilib/ client.c
>> > > +// RUN: %clang_cc1 -include-pch pch -Ilib/ client.c -fsyntax-only
>> > >
>> > > Modified: cfe/trunk/unittests/Basic/FileManagerTest.cpp
>> > > URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/unittests/Basic/FileManagerTest.cpp?rev=352079&r1=352078&r2=352079&view=diff
>> > > ==============================================================================
>> > > --- cfe/trunk/unittests/Basic/FileManagerTest.cpp (original)
>> > > +++ cfe/trunk/unittests/Basic/FileManagerTest.cpp Thu Jan 24 10:55:24 2019
>> > > @@ -221,33 +221,6 @@ TEST_F(FileManagerTest, getFileReturnsNU
>> > > EXPECT_EQ(nullptr, file);
>> > > }
>> > >
>> > > -// When calling getFile(OpenFile=false); getFile(OpenFile=true) the file is
>> > > -// opened for the second call.
>> > > -TEST_F(FileManagerTest, getFileDefersOpen) {
>> > > - llvm::IntrusiveRefCntPtr<llvm::vfs::InMemoryFileSystem> FS(
>> > > - new llvm::vfs::InMemoryFileSystem());
>> > > - FS->addFile("/tmp/test", 0, llvm::MemoryBuffer::getMemBufferCopy("test"));
>> > > - FS->addFile("/tmp/testv", 0, llvm::MemoryBuffer::getMemBufferCopy("testv"));
>> > > - FileManager manager(options, FS);
>> > > -
>> > > - const FileEntry *file = manager.getFile("/tmp/test", /*OpenFile=*/false);
>> > > - ASSERT_TRUE(file != nullptr);
>> > > - ASSERT_TRUE(file->isValid());
>> > > - // "real path name" reveals whether the file was actually opened.
>> > > - EXPECT_FALSE(file->isOpenForTests());
>> > > -
>> > > - file = manager.getFile("/tmp/test", /*OpenFile=*/true);
>> > > - ASSERT_TRUE(file != nullptr);
>> > > - ASSERT_TRUE(file->isValid());
>> > > - EXPECT_TRUE(file->isOpenForTests());
>> > > -
>> > > - // However we should never try to open a file previously opened as virtual.
>> > > - ASSERT_TRUE(manager.getVirtualFile("/tmp/testv", 5, 0));
>> > > - ASSERT_TRUE(manager.getFile("/tmp/testv", /*OpenFile=*/false));
>> > > - file = manager.getFile("/tmp/testv", /*OpenFile=*/true);
>> > > - EXPECT_FALSE(file->isOpenForTests());
>> > > -}
>> > > -
>> > > // The following tests apply to Unix-like system only.
>> > >
>> > > #ifndef _WIN32
>> > >
>> > >
>> > > _______________________________________________
>> > > cfe-commits mailing list
>> > > cfe-commits at lists.llvm.org
>> > > https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
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