From a08f67b5450da6cf7ed8255be55a36834c9b81be Mon Sep 17 00:00:00 2001
From: Ye Luo <yeluo@anl.gov>
Date: Tue, 9 Jan 2018 14:18:10 -0600
Subject: [PATCH] Overwrite maxCopy to 2 if it is larger and nonblocking=yes.

---
 manual/dmc.tex                       | 2 +-
 src/QMCDrivers/WalkerControlBase.cpp | 8 ++++++--
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/manual/dmc.tex b/manual/dmc.tex
index f154b9fbc..e0e32c2aa 100644
--- a/manual/dmc.tex
+++ b/manual/dmc.tex
@@ -46,7 +46,7 @@
  %  &   \texttt{wlen                } &  integer  & $\ge 0$ & 0   & number of samples per  thread  \\
    &   \texttt{maxDisplSq      } &  real  & all values & -1   & maximum particle move  \\
    &   \texttt{storeconfigs        } &  integer  & all values & 0   & store configurations  \\
-   &   \texttt{use\_nonblocking    } &  string  & yes/no & no   & using non-blocking send/recv \\
+   &   \texttt{use\_nonblocking    } &  string  & yes/no & yes   & using non-blocking send/recv \\
    &   \texttt{blocks\_between\_recompute} &  integer  & $\ge 0$ & dep.  & wavefunction recompute frequency  \\
   \hline
 \end{tabularx}
diff --git a/src/QMCDrivers/WalkerControlBase.cpp b/src/QMCDrivers/WalkerControlBase.cpp
index ad97d52b1..887052697 100644
--- a/src/QMCDrivers/WalkerControlBase.cpp
+++ b/src/QMCDrivers/WalkerControlBase.cpp
@@ -502,7 +502,7 @@ int WalkerControlBase::copyWalkers(MCWalkerConfiguration& W)
 bool WalkerControlBase::put(xmlNodePtr cur)
 {
   int nw_target=0, nw_max=0;
-  std::string nonblocking="no";
+  std::string nonblocking="yes";
   ParameterSet params;
   params.add(targetEnergyBound,"energyBound","double");
   params.add(targetSigma,"sigmaBound","double");
@@ -516,8 +516,12 @@ bool WalkerControlBase::put(xmlNodePtr cur)
   // validating input
   if(nonblocking=="yes")
   {
-    APP_ABORT("WalkerControlBase::put use_nonblocking==\"yes\" is disabled currently!");
     use_nonblocking = true;
+    if(MaxCopy>2)
+    {
+      app_warning() << "use_nonblocking==\"yes\" doesn't support maxCopy>2. Overwriting it to 2." << std::endl;
+      MaxCopy=2;
+    }
   }
   else if(nonblocking=="no")
   {