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Merge pull request #2384 from citusdata/fix_stuck_spinlock_max_backend 

Prevent overflow of memory accesses during deadlock detection
pull/2376/head
Önder Kalacı 2018-09-17 18:08:31 +03:00 committed by GitHub
parent e0942d9df5 a94184fff8
commit 8762af4473
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GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 14 additions and 8 deletions
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8
src/backend/distributed/transaction/backend_data.c
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@ -541,9 +541,11 @@ BackendManagementShmemInit(void)
/*
* We need to init per backend's spinlock before any backend
* starts its execution.
* starts its execution. Note that we initialize TotalProcs (e.g., not
* MaxBackends) since some of the blocking processes could be prepared
* transactions, which aren't covered by MaxBackends.
*/
for (backendIndex = 0; backendIndex < MaxBackends; ++backendIndex)
for (backendIndex = 0; backendIndex < TotalProcs; ++backendIndex)
{
SpinLockInit(&backendManagementShmemData->backends[backendIndex].mutex);
}
@ -568,7 +570,7 @@ BackendManagementShmemSize(void)
Size size = 0;
size = add_size(size, sizeof(BackendManagementShmemData));
size = add_size(size, mul_size(sizeof(BackendData), MaxBackends));
size = add_size(size, mul_size(sizeof(BackendData), TotalProcs));
return size;
}

10
src/backend/distributed/transaction/lock_graph.c
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@ -398,12 +398,12 @@ BuildLocalWaitGraph(void)
*/
waitGraph = (WaitGraph *) palloc0(sizeof(WaitGraph));
waitGraph->localNodeId = GetLocalGroupId();
waitGraph->allocatedSize = MaxBackends * 3;
waitGraph->allocatedSize = TotalProcs * 3;
waitGraph->edgeCount = 0;
waitGraph->edges = (WaitEdge *) palloc(waitGraph->allocatedSize * sizeof(WaitEdge));
remaining.procs = (PGPROC **) palloc(sizeof(PGPROC *) * MaxBackends);
remaining.procAdded = (bool *) palloc0(sizeof(bool *) * MaxBackends);
remaining.procs = (PGPROC **) palloc(sizeof(PGPROC *) * TotalProcs);
remaining.procAdded = (bool *) palloc0(sizeof(bool *) * TotalProcs);
remaining.procCount = 0;
LockLockData();
@ -416,7 +416,7 @@ BuildLocalWaitGraph(void)
*/
/* build list of starting procs */
for (curBackend = 0; curBackend < MaxBackends; curBackend++)
for (curBackend = 0; curBackend < TotalProcs; curBackend++)
{
PGPROC *currentProc = &ProcGlobal->allProcs[curBackend];
BackendData currentBackendData;
@ -762,7 +762,7 @@ AddProcToVisit(PROCStack *remaining, PGPROC *proc)
return;
}
Assert(remaining->procCount < MaxBackends);
Assert(remaining->procCount < TotalProcs);
remaining->procs[remaining->procCount++] = proc;
remaining->procAdded[proc->pgprocno] = true;

4
src/include/distributed/backend_data.h
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@ -13,6 +13,7 @@
#define BACKEND_DATA_H
#include "access/twophase.h"
#include "datatype/timestamp.h"
#include "distributed/transaction_identifier.h"
#include "nodes/pg_list.h"
@ -21,6 +22,9 @@
#include "storage/s_lock.h"
#define TotalProcs (MaxBackends + NUM_AUXILIARY_PROCS + max_prepared_xacts)
/*
* Each backend's active distributed transaction information is tracked via
* BackendData in shared memory.