diff --git a/trunk/research/thread-model/.gitignore b/trunk/research/thread-model/.gitignore
index 1abd1fc862..5737fff3e8 100644
--- a/trunk/research/thread-model/.gitignore
+++ b/trunk/research/thread-model/.gitignore
@@ -1,3 +1,4 @@
 thread-local
 udp-connect-client
 udp-connect-server
+extern-main
diff --git a/trunk/research/thread-model/extern-extra.cpp b/trunk/research/thread-model/extern-extra.cpp
new file mode 100644
index 0000000000..f203776488
--- /dev/null
+++ b/trunk/research/thread-model/extern-extra.cpp
@@ -0,0 +1,13 @@
+
+#include <stdio.h>
+
+int __thread ga = 100;
+int __thread gb = 200;
+
+void* pfn2(void* arg)
+{
+    printf("Thread2: ga=%d, gb=%d\n", ga, gb);
+    return NULL;
+}
+
+
diff --git a/trunk/research/thread-model/extern-main.cpp b/trunk/research/thread-model/extern-main.cpp
new file mode 100644
index 0000000000..33c4f446f9
--- /dev/null
+++ b/trunk/research/thread-model/extern-main.cpp
@@ -0,0 +1,36 @@
+/*
+g++ -std=c++11 -g -O0 extern-main.cpp extern-extra.cpp -o extern-main
+*/
+#include <stdio.h>
+// @see https://linux.die.net/man/3/pthread_create
+#include <pthread.h>
+
+/*
+Main: ga=100, gb=1867710016
+Thread1: ga=100, gb=1867710016
+Thread2: ga=100, gb=200
+*/
+extern __thread int ga;
+extern int gb;
+
+void* pfn(void* arg)
+{
+    printf("Thread1: ga=%d, gb=%d\n", ga, gb);
+    return NULL;
+}
+
+extern void* pfn2(void* arg);
+
+int main(int argc, char** argv)
+{
+    printf("Main: ga=%d, gb=%d\n", ga, gb);
+
+    pthread_t trd = NULL;
+    pthread_create(&trd, NULL, pfn, NULL);
+    pthread_join(trd, NULL);
+
+    pthread_t trd2 = NULL;
+    pthread_create(&trd2, NULL, pfn2, NULL);
+    pthread_join(trd2, NULL);
+    return 0;
+}