Merge pull request #6424 from str4d/sideport-reindex-lock-contention-fix-5.4.1

Sleep for 200µs before each `ActivateBestChainStep` call

src/main.cpp

@@ -27,6 +27,7 @@
 #include "policy/policy.h"
 #include "pow.h"
 #include "reverse_iterator.h"
+#include "time.h"
 #include "txmempool.h"
 #include "ui_interface.h"
 #include "undo.h"
@@ -4386,7 +4387,17 @@ bool ActivateBestChain(CValidationState& state, const CChainParams& chainparams,
     CBlockIndex *pindexMostWork = NULL;
     CBlockIndex *pindexNewTip = NULL;
     do {
-        boost::this_thread::interruption_point();
+        // Sleep briefly to allow other threads a chance at grabbing cs_main if
+        // we are connecting a long chain of blocks and would otherwise hold the
+        // lock almost continuously. As of 2023-02-03 the Zcash mainnet chain is
+        // around height 1,972,000; the total time slept here while activating
+        // the best chain from genesis to that height is ~6.6 minutes. This helps
+        // the internal wallet, if it is enabled, to keep up with the connected
+        // blocks, reducing the overall time until the node becomes usable.
+        //
+        // This is defined to be an interruption point.
+        // <https://www.boost.org/doc/libs/1_81_0/doc/html/thread/thread_management.html#interruption_points>
+        boost::this_thread::sleep_for(boost::chrono::microseconds(200));
 
         bool fInitialDownload;
         int nNewHeight;