Multithreading support

Makefile.in

@@ -90,6 +90,7 @@ host_triplet = @host@
 subdir = .
 ACLOCAL_M4 = $(top_srcdir)/aclocal.m4
 am__aclocal_m4_deps = $(top_srcdir)/config/ax_check_openssl.m4 \
+	$(top_srcdir)/config/ax_pthread.m4 \
 	$(top_srcdir)/config/iperf_config_static_bin.m4 \
 	$(top_srcdir)/configure.ac
 am__configure_deps = $(am__aclocal_m4_deps) $(CONFIGURE_DEPENDENCIES) \
@@ -219,6 +220,7 @@ AWK = @AWK@
 CC = @CC@
 CCDEPMODE = @CCDEPMODE@
 CFLAGS = @CFLAGS@
+CPP = @CPP@
 CPPFLAGS = @CPPFLAGS@
 CSCOPE = @CSCOPE@
 CTAGS = @CTAGS@
@@ -273,6 +275,10 @@ PACKAGE_URL = @PACKAGE_URL@
 PACKAGE_VERSION = @PACKAGE_VERSION@
 PATH_SEPARATOR = @PATH_SEPARATOR@
 PKG_CONFIG = @PKG_CONFIG@
+PTHREAD_CC = @PTHREAD_CC@
+PTHREAD_CFLAGS = @PTHREAD_CFLAGS@
+PTHREAD_CXX = @PTHREAD_CXX@
+PTHREAD_LIBS = @PTHREAD_LIBS@
 RANLIB = @RANLIB@
 SED = @SED@
 SET_MAKE = @SET_MAKE@
@@ -291,6 +297,7 @@ am__leading_dot = @am__leading_dot@
 am__quote = @am__quote@
 am__tar = @am__tar@
 am__untar = @am__untar@
+ax_pthread_config = @ax_pthread_config@
 bindir = @bindir@
 build = @build@
 build_alias = @build_alias@

RELNOTES.md

@@ -1,6 +1,38 @@
 iperf3 Release Notes
 ====================
 
+iperf-3.15-mt-beta1 2023-09-29
+------------------------------
+Accumulated release notes from iperf-3.14 and earlier multithreaded
+beta releases:
+
+* Notable user-visible changes
+
+  * Multiple test streams started with -P/--parallel will now be
+    serviced by different threads. This allows iperf3 to take
+    advantage of multiple CPU cores on modern processors.
+
+  * Remove some busy-waiting left over from the original
+    single-threaded implementation, which caused the multi-threaded
+    iperf3 to consume CPU resources for no particular reason, and
+    possible subsequent packet loss.
+
+  * CentOS 7's default compiler is a version of GCC that is too old to
+    compile code using C11 atomic variables. A workaround has been
+    devised for 64-bit CentOS 7 systems, it is not clear whether this
+    approach will work on 32-bit CentOS 7 hosts, or other
+    similarly-vintage build environment.
+
+  * Fix a bug related to idle timeouts, so that the --rcv-timeout
+    option works correctly.
+
+  * Make shutdown of threads more tolerant in the face of various
+    orders of operations at the end of tests.
+
+* Developer-visible changes
+
+  * iperf3 requires pthreads and C atomic variables to compile and run.
+
 iperf-3.15 2023-09-14
 ---------------------