From 0cc465d39f79c5ace6c16f570d6f1cacfa879060 Mon Sep 17 00:00:00 2001
From: James Turner <james@flightgear.org>
Date: Fri, 5 Feb 2021 11:14:34 +0000
Subject: [PATCH] Tweak Natural-earth loading to reduce DB contention
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Reduce ‘SQLITE BUSY’ issues with multiple running copies of FG
---
src/GUI/QtLauncher.cxx | 8 ++++++--
src/Navaids/NavDataCache.cxx | 5 ++++-
2 files changed, 10 insertions(+), 3 deletions(-)
diff --git a/src/GUI/QtLauncher.cxx b/src/GUI/QtLauncher.cxx
index a9bbe10b0..baf5de35f 100644
--- a/src/GUI/QtLauncher.cxx
+++ b/src/GUI/QtLauncher.cxx
@@ -218,14 +218,18 @@ private:
return;
flightgear::PolyLineList::const_iterator begin = m_parsedLines.begin() + m_lineInsertCount;
- unsigned int numToAdd = std::min<unsigned int>(1000U, static_cast<unsigned int>(m_parsedLines.size()) - m_lineInsertCount);
+
+ // add lines in batches of 100; this is a tradeoff to ensure we don't lock
+ // the database for too long. (Which triggers SQLITE_BUSY)
+ const int lineInsertBatchSize = 100U;
+ unsigned int numToAdd = std::min<unsigned int>(100U, static_cast<unsigned int>(m_parsedLines.size()) - m_lineInsertCount);
flightgear::PolyLineList::const_iterator end = begin + numToAdd;
flightgear::PolyLine::bulkAddToSpatialIndex(begin, end);
if (end == m_parsedLines.end()) {
deleteLater(); // commit suicide
} else {
- m_lineInsertCount += 1000;
+ m_lineInsertCount += lineInsertBatchSize;
QTimer::singleShot(50, this, SLOT(onFinished()));
}
}
diff --git a/src/Navaids/NavDataCache.cxx b/src/Navaids/NavDataCache.cxx
index 1e28d691e..e5f1d4f63 100644
--- a/src/Navaids/NavDataCache.cxx
+++ b/src/Navaids/NavDataCache.cxx
@@ -458,6 +458,8 @@ public:
{
int retries = 0;
int result;
+ int retryMSec = 10;
+
while (retries < MAX_RETRIES) {
result = sqlite3_step(stmt);
if (result == SQLITE_ROW) {
@@ -473,7 +475,8 @@ public:
}
SG_LOG(SG_NAVCACHE, SG_ALERT, "NavCache contention on select, will retry:" << retries);
- SGTimeStamp::sleepForMSec(++retries * 10);
+ SGTimeStamp::sleepForMSec(retryMSec);
+ retryMSec *= 2; // double the back-off time, each time
} // of retry loop for DB locked
if (retries >= MAX_RETRIES) {