First-pass IMT implementation of FlushBaskets. #277
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| Original file line number | Diff line number | Diff line change |
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@@ -1336,17 +1336,17 @@ Long64_t TTree::AutoSave(Option_t* option) | |
| { | ||
| if (!fDirectory || fDirectory == gROOT || !fDirectory->IsWritable()) return 0; | ||
| if (gDebug > 0) { | ||
| Info("AutoSave", "Tree:%s after %lld bytes written\n",GetName(),GetTotBytes()); | ||
| } | ||
| TString opt = option; | ||
| opt.ToLower(); | ||
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| if (opt.Contains("flushbaskets")) { | ||
| if (gDebug > 0) Info("AutoSave", "calling FlushBaskets \n"); | ||
| FlushBaskets(); | ||
| } | ||
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| fSavedBytes = GetZipBytes(); | ||
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| TKey *key = (TKey*)fDirectory->GetListOfKeys()->FindObject(GetName()); | ||
| Long64_t nbytes; | ||
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@@ -3608,7 +3608,7 @@ void TTree::Delete(Option_t* option /* = "" */) | |
| key = fDirectory->GetKey(GetName()); | ||
| } | ||
| if (dirsav) dirsav->cd(); | ||
| if (gDebug) Info("TTree::Delete", "Deleting Tree: %s: %d baskets deleted. Total space freed = %d bytes\n",GetName(),nbask,ntot); | ||
| } | ||
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| if (fDirectory) { | ||
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@@ -4417,35 +4417,37 @@ Int_t TTree::Fill() | |
| if (fEntries > fMaxEntries) { | ||
| KeepCircular(); | ||
| } | ||
| if (gDebug > 0) Info("TTree::Fill", " - A: %d %lld %lld %lld %lld %lld %lld \n", | ||
| nbytes, fEntries, fAutoFlush,fAutoSave,GetZipBytes(),fFlushedBytes,fSavedBytes); | ||
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| if (fAutoFlush != 0 || fAutoSave != 0) { | ||
| // Is it time to flush or autosave baskets? | ||
| if (fFlushedBytes == 0) { | ||
| // Decision can be based initially either on the number of bytes | ||
| // or the number of entries written. | ||
| Long64_t zipBytes = GetZipBytes(); | ||
| if ((fAutoFlush<0 && zipBytes > -fAutoFlush) || | ||
| (fAutoSave <0 && zipBytes > -fAutoSave ) || | ||
| (fAutoFlush>0 && fEntries%TMath::Max((Long64_t)1,fAutoFlush) == 0) || | ||
| (fAutoSave >0 && fEntries%TMath::Max((Long64_t)1,fAutoSave) == 0) ) { | ||
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| //First call FlushBasket to make sure that fTotBytes is up to date. | ||
| FlushBaskets(); | ||
| OptimizeBaskets(GetTotBytes(),1,""); | ||
| if (gDebug > 0) Info("TTree::Fill","OptimizeBaskets called at entry %lld, fZipBytes=%lld, fFlushedBytes=%lld\n",fEntries,GetZipBytes(),fFlushedBytes); | ||
| fFlushedBytes = GetZipBytes(); | ||
| fAutoFlush = fEntries; // Use test on entries rather than bytes | ||
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| // subsequently in run | ||
| if (fAutoSave < 0) { | ||
| // Set fAutoSave to the largest integer multiple of | ||
| // fAutoFlush events such that fAutoSave*fFlushedBytes | ||
| // < (minus the input value of fAutoSave) | ||
| Long64_t totBytes = GetTotBytes(); | ||
| if (zipBytes != 0) { | ||
| fAutoSave = TMath::Max( fAutoFlush, fEntries*((-fAutoSave/zipBytes)/fEntries)); | ||
| } else if (totBytes != 0) { | ||
| fAutoSave = TMath::Max( fAutoFlush, fEntries*((-fAutoSave/totBytes)/fEntries)); | ||
| } else { | ||
| TBufferFile b(TBuffer::kWrite, 10000); | ||
| TTree::Class()->WriteBuffer(b, (TTree*) this); | ||
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@@ -4462,24 +4464,24 @@ Int_t TTree::Fill() | |
| if (fAutoSave != 0 && fEntries%fAutoSave == 0) { | ||
| //We are at an AutoSave point. AutoSave flushes baskets and saves the Tree header | ||
| AutoSave("flushbaskets"); | ||
| if (gDebug > 0) Info("TTree::Fill","AutoSave called at entry %lld, fZipBytes=%lld, fSavedBytes=%lld\n",fEntries,GetZipBytes(),fSavedBytes); | ||
| } else { | ||
| //We only FlushBaskets | ||
| FlushBaskets(); | ||
| if (gDebug > 0) Info("TTree::Fill","FlushBasket called at entry %lld, fZipBytes=%lld, fFlushedBytes=%lld\n",fEntries,GetZipBytes(),fFlushedBytes); | ||
| } | ||
| fFlushedBytes = GetZipBytes(); | ||
| } else if (fNClusterRange == 0 && fEntries > 1 && fAutoFlush && fEntries%fAutoFlush == 0) { | ||
| if (fAutoSave != 0 && fEntries%fAutoSave == 0) { | ||
| //We are at an AutoSave point. AutoSave flushes baskets and saves the Tree header | ||
| AutoSave("flushbaskets"); | ||
| if (gDebug > 0) Info("TTree::Fill","AutoSave called at entry %lld, fZipBytes=%lld, fSavedBytes=%lld\n",fEntries,GetZipBytes(),fSavedBytes); | ||
| } else { | ||
| //We only FlushBaskets | ||
| FlushBaskets(); | ||
| if (gDebug > 0) Info("TTree::Fill","FlushBasket called at entry %lld, fZipBytes=%lld, fFlushedBytes=%lld\n",fEntries,GetZipBytes(),fFlushedBytes); | ||
| } | ||
| fFlushedBytes = GetZipBytes(); | ||
| } | ||
| } | ||
| // Check that output file is still below the maximum size. | ||
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@@ -4790,6 +4792,16 @@ Int_t TTree::Fit(const char* funcname, const char* varexp, const char* selection | |
| return -1; | ||
| } | ||
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| struct BoolRAIIToggle { | ||
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Member
There was a problem hiding this comment. Consider putting this class in the anonymous namespace. |
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| Bool_t &m_val; | ||
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| BoolRAIIToggle(Bool_t &val) : m_val(val) { m_val = true; } | ||
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| ~BoolRAIIToggle() { m_val = false; } | ||
| }; | ||
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| //////////////////////////////////////////////////////////////////////////////// | ||
| /// Write to disk all the basket that have not yet been individually written. | ||
| /// | ||
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@@ -4802,6 +4814,53 @@ Int_t TTree::FlushBaskets() const | |
| Int_t nerror = 0; | ||
| TObjArray *lb = const_cast<TTree*>(this)->GetListOfBranches(); | ||
| Int_t nb = lb->GetEntriesFast(); | ||
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| #ifdef R__USE_IMT | ||
| if (ROOT::IsImplicitMTEnabled() && fIMTEnabled) { | ||
| if (fSortedBranches.empty()) { const_cast<TTree*>(this)->InitializeSortedBranches(); } | ||
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| BoolRAIIToggle sentry(fIMTFlush); | ||
| fIMTZipBytes.store(0); | ||
| fIMTTotBytes.store(0); | ||
| std::atomic<Int_t> nerrpar(0); | ||
| std::atomic<Int_t> nbpar(0); | ||
| std::atomic<Int_t> pos(0); | ||
| tbb::task_group g; | ||
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Collaborator
There was a problem hiding this comment. We must be extremely careful when embedding calls to TBB into legacy code. Holding any shared resource (which a C++ object itself may be viewed as such a resource) can lead to deadlocks. See https://software.intel.com/en-us/forums/intel-threading-building-blocks/topic/401006 for details. This is one reason why the CMS threaded-framework is built using explicit tasks rather than implicit ones. For the case of writing, I can't think of anyone being dependent on the TFile, although we must be certain that no ROOT locks are being held by the thread calling
Contributor
Author
There was a problem hiding this comment. Hi Chris, Indeed. My logic here is:
So, the remaining danger is if the caller (CMSSW) is holding a mutex of its own that other CMSSW tasks might need. I will write these concerns up into a comment, provide an example of dangerous behavior, and add them to the function's documentation. Brian
Contributor
Author
There was a problem hiding this comment. Here's an example of a deadlock that could have happened in older versions of CMSSW:
Now, Chris tells me that CMSSW has switched away from the mutex for output module access - but this might be a good example. I pushed a long comment for
Member
There was a problem hiding this comment.
This of course depend on whether the mutex that is used is recursive or not (TMutex is, std::mutex is not).
Contributor
Author
There was a problem hiding this comment. Certainly! The point is that working code with IMT-disabled may stop working when IMT is enabled. One would hope that issues would be fixable once the user understands the underlying issue. Hence the extensive comment in the code. |
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| for (Int_t i = 0; i < nb; i++) { | ||
| g.run([&]() { | ||
| // The branch to process is obtained when the task starts to run. | ||
| // This way, since branches are sorted, we make sure that branches | ||
| // leading to big tasks are processed first. If we assigned the | ||
| // branch at task creation time, the scheduler would not necessarily | ||
| // respect our sorting. | ||
| Int_t j = pos.fetch_add(1); | ||
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| auto branch = fSortedBranches[j].second; | ||
| if (R__unlikely(!branch)) { return; } | ||
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| if (R__unlikely(gDebug > 0)) { | ||
| std::stringstream ss; | ||
| ss << std::this_thread::get_id(); | ||
| Info("FlushBaskets", "[IMT] Thread %s", ss.str().c_str()); | ||
| Info("FlushBaskets", "[IMT] Running task for branch #%d: %s", j, branch->GetName()); | ||
| } | ||
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| Int_t nbtask = branch->FlushBaskets(); | ||
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| if (nbtask < 0) { nerrpar++; } | ||
| else { nbpar += nbtask; } | ||
| }); | ||
| } | ||
| g.wait(); | ||
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| fIMTFlush = false; | ||
| const_cast<TTree*>(this)->AddTotBytes(fIMTTotBytes); | ||
| const_cast<TTree*>(this)->AddZipBytes(fIMTZipBytes); | ||
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| return nerrpar ? -1 : nbpar.load(); | ||
| } | ||
| #endif | ||
| for (Int_t j = 0; j < nb; j++) { | ||
| TBranch* branch = (TBranch*) lb->UncheckedAt(j); | ||
| if (branch) { | ||
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@@ -5006,7 +5065,7 @@ Long64_t TTree::GetCacheAutoSize(Bool_t withDefault /* = kFALSE */ ) const | |
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| if (fAutoFlush < 0) cacheSize = Long64_t(-cacheFactor*fAutoFlush); | ||
| else if (fAutoFlush == 0) cacheSize = 0; | ||
| else cacheSize = Long64_t(cacheFactor*1.5*fAutoFlush*GetZipBytes()/(fEntries+1)); | ||
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| if (cacheSize >= (INT_MAX / 4)) { | ||
| cacheSize = INT_MAX / 4; | ||
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@@ -5019,7 +5078,7 @@ Long64_t TTree::GetCacheAutoSize(Bool_t withDefault /* = kFALSE */ ) const | |
| if (cacheSize == 0 && withDefault) { | ||
| if (fAutoFlush < 0) cacheSize = -fAutoFlush; | ||
| else if (fAutoFlush == 0) cacheSize = 0; | ||
| else cacheSize = Long64_t(1.5*fAutoFlush*GetZipBytes()/(fEntries+1)); | ||
| } | ||
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| return cacheSize; | ||
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@@ -6600,7 +6659,7 @@ void TTree::OptimizeBaskets(ULong64_t maxMemory, Float_t minComp, Option_t *opti | |
| if (newBsize < bmin) newBsize = bmin; | ||
| if (newBsize > 10000000) newBsize = bmax; | ||
| if (pass) { | ||
| if (pDebug) Info("OptimizeBaskets", "Changing buffer size from %6d to %6d bytes for %s\n",oldBsize,newBsize,branch->GetName()); | ||
| branch->SetBasketSize(newBsize); | ||
| } | ||
| newMemsize += newBsize; | ||
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@@ -6613,7 +6672,7 @@ void TTree::OptimizeBaskets(ULong64_t maxMemory, Float_t minComp, Option_t *opti | |
| Double_t comp = 1; | ||
| if (branch->GetZipBytes() > 0) comp = totBytes/Double_t(branch->GetZipBytes()); | ||
| if (comp > 1 && comp < minComp) { | ||
| if (pDebug) Info("OptimizeBaskets", "Disabling compression for branch : %s\n",branch->GetName()); | ||
| branch->SetCompressionSettings(0); | ||
| } | ||
| } | ||
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@@ -6634,8 +6693,8 @@ void TTree::OptimizeBaskets(ULong64_t maxMemory, Float_t minComp, Option_t *opti | |
| bmax = (bmax_new > hardmax) ? bmin : (UInt_t)bmax_new; | ||
| } | ||
| if (pDebug) { | ||
| Info("OptimizeBaskets", "oldMemsize = %d, newMemsize = %d\n",oldMemsize, newMemsize); | ||
| Info("OptimizeBaskets", "oldBaskets = %d, newBaskets = %d\n",oldBaskets, newBaskets); | ||
| } | ||
| } | ||
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@@ -6702,16 +6761,17 @@ void TTree::Print(Option_t* option) const | |
| } | ||
| } | ||
| Long64_t total = skey; | ||
| Long64_t zipBytes = GetZipBytes(); | ||
| if (zipBytes > 0) { | ||
| total += GetTotBytes(); | ||
| } | ||
| TBufferFile b(TBuffer::kWrite, 10000); | ||
| TTree::Class()->WriteBuffer(b, (TTree*) this); | ||
| total += b.Length(); | ||
| Long64_t file = zipBytes + s; | ||
| Float_t cx = 1; | ||
| if (zipBytes) { | ||
| cx = (GetTotBytes() + 0.00001) / zipBytes; | ||
| } | ||
| Printf("******************************************************************************"); | ||
| Printf("*Tree :%-10s: %-54s *", GetName(), GetTitle()); | ||
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@@ -6758,7 +6818,7 @@ void TTree::Print(Option_t* option) const | |
| if (count[l] < 0) continue; | ||
| leaf = (TLeaf *)const_cast<TTree*>(this)->GetListOfLeaves()->At(l); | ||
| br = leaf->GetBranch(); | ||
| Printf("branch: %-20s %9lld\n",br->GetName(),count[l]); | ||
| } | ||
| delete [] count; | ||
| } else { | ||
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@@ -7352,8 +7412,8 @@ void TTree::Refresh() | |
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| fAutoSave = tree->fAutoSave; | ||
| fEntries = tree->fEntries; | ||
| fTotBytes = tree->GetTotBytes(); | ||
| fZipBytes = tree->GetZipBytes(); | ||
| fSavedBytes = tree->fSavedBytes; | ||
| fTotalBuffers = tree->fTotalBuffers.load(); | ||
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@@ -8823,10 +8883,12 @@ void TTree::Streamer(TBuffer& b) | |
| } else if (fAutoFlush != 0) { | ||
| // Estimate the cluster size. | ||
| // This will allow TTree::Process to enable the cache. | ||
| Long64_t zipBytes = GetZipBytes(); | ||
| Long64_t totBytes = GetTotBytes(); | ||
| if (zipBytes != 0) { | ||
| fCacheSize = fAutoFlush*(zipBytes/fEntries); | ||
| } else if (totBytes != 0) { | ||
| fCacheSize = fAutoFlush*(totBytes/fEntries); | ||
| } else { | ||
| fCacheSize = 30000000; | ||
| } | ||
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I don't see
#include <mutex>?There was a problem hiding this comment.
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Fixed.