binder: RpcSession limit outgoing threads
Similar to the number of incoming threads,
the number of outgoing threads can be limited via
RpcSession::setMaxOutgoingThreads(). If set, only
min(maxOutgoingThreads, remoteMaxThreads) outgoing threads
are instantiated.
Test: binderRpcTest
Bug: 194225767
Change-Id: I15686bae4317d0ced5af999f3a3d21f9a03037e1
diff --git a/libs/binder/RpcSession.cpp b/libs/binder/RpcSession.cpp
index 486b67b..9eef3e8 100644
--- a/libs/binder/RpcSession.cpp
+++ b/libs/binder/RpcSession.cpp
@@ -90,6 +90,20 @@
return mMaxIncomingThreads;
}
+void RpcSession::setMaxOutgoingThreads(size_t threads) {
+ std::lock_guard<std::mutex> _l(mMutex);
+ LOG_ALWAYS_FATAL_IF(!mConnections.mOutgoing.empty() || !mConnections.mIncoming.empty(),
+ "Must set max outgoing threads before setting up connections, but has %zu "
+ "client(s) and %zu server(s)",
+ mConnections.mOutgoing.size(), mConnections.mIncoming.size());
+ mMaxOutgoingThreads = threads;
+}
+
+size_t RpcSession::getMaxOutgoingThreads() {
+ std::lock_guard<std::mutex> _l(mMutex);
+ return mMaxOutgoingThreads;
+}
+
bool RpcSession::setProtocolVersion(uint32_t version) {
if (version >= RPC_WIRE_PROTOCOL_VERSION_NEXT &&
version != RPC_WIRE_PROTOCOL_VERSION_EXPERIMENTAL) {
@@ -473,6 +487,12 @@
return status;
}
+ size_t outgoingThreads = std::min(numThreadsAvailable, mMaxOutgoingThreads);
+ ALOGI_IF(outgoingThreads != numThreadsAvailable,
+ "Server hints client to start %zu outgoing threads, but client will only start %zu "
+ "because it is preconfigured to start at most %zu outgoing threads.",
+ numThreadsAvailable, outgoingThreads, mMaxOutgoingThreads);
+
// TODO(b/189955605): we should add additional sessions dynamically
// instead of all at once - the other side should be responsible for setting
// up additional connections. We need to create at least one (unless 0 are
@@ -480,7 +500,10 @@
// any requests at all.
// we've already setup one client
- for (size_t i = 0; i + 1 < numThreadsAvailable; i++) {
+ LOG_RPC_DETAIL("RpcSession::setupClient() instantiating %zu outgoing (server max: %zu) and %zu "
+ "incoming threads",
+ outgoingThreads, numThreadsAvailable, mMaxIncomingThreads);
+ for (size_t i = 0; i + 1 < outgoingThreads; i++) {
if (status_t status = connectAndInit(mId, false /*incoming*/); status != OK) return status;
}
diff --git a/libs/binder/include/binder/RpcSession.h b/libs/binder/include/binder/RpcSession.h
index e64572b..f5505da 100644
--- a/libs/binder/include/binder/RpcSession.h
+++ b/libs/binder/include/binder/RpcSession.h
@@ -50,6 +50,8 @@
*/
class RpcSession final : public virtual RefBase {
public:
+ static constexpr size_t kDefaultMaxOutgoingThreads = 10;
+
// Create an RpcSession with default configuration (raw sockets).
static sp<RpcSession> make();
@@ -72,6 +74,18 @@
size_t getMaxIncomingThreads();
/**
+ * Set the maximum number of outgoing threads allowed to be made.
+ * By default, this is |kDefaultMaxOutgoingThreads|. This must be called before setting up this
+ * connection as a client.
+ *
+ * This limits the number of outgoing threads on top of the remote peer setting. This RpcSession
+ * will only instantiate |min(maxOutgoingThreads, remoteMaxThreads)| outgoing threads, where
+ * |remoteMaxThreads| can be retrieved from the remote peer via |getRemoteMaxThreads()|.
+ */
+ void setMaxOutgoingThreads(size_t threads);
+ size_t getMaxOutgoingThreads();
+
+ /**
* By default, the minimum of the supported versions of the client and the
* server will be used. Usually, this API should only be used for debugging.
*/
@@ -308,6 +322,7 @@
std::mutex mMutex; // for all below
size_t mMaxIncomingThreads = 0;
+ size_t mMaxOutgoingThreads = kDefaultMaxOutgoingThreads;
std::optional<uint32_t> mProtocolVersion;
std::condition_variable mAvailableConnectionCv; // for mWaitingThreads
diff --git a/libs/binder/tests/binderRpcTest.cpp b/libs/binder/tests/binderRpcTest.cpp
index 2011801..d68c6ff 100644
--- a/libs/binder/tests/binderRpcTest.cpp
+++ b/libs/binder/tests/binderRpcTest.cpp
@@ -481,6 +481,7 @@
size_t numThreads = 1;
size_t numSessions = 1;
size_t numIncomingConnections = 0;
+ size_t numOutgoingConnections = SIZE_MAX;
};
static inline std::string PrintParamInfo(const testing::TestParamInfo<ParamType>& info) {
@@ -614,6 +615,7 @@
for (const auto& session : sessions) {
session->setMaxIncomingThreads(options.numIncomingConnections);
+ session->setMaxOutgoingThreads(options.numOutgoingConnections);
switch (socketType) {
case SocketType::PRECONNECTED:
@@ -655,6 +657,9 @@
return ret;
}
+
+ void testThreadPoolOverSaturated(sp<IBinderRpcTest> iface, size_t numCalls,
+ size_t sleepMs = 500);
};
TEST_P(BinderRpc, Ping) {
@@ -996,28 +1001,39 @@
for (auto& t : ts) t.join();
}
-TEST_P(BinderRpc, ThreadPoolOverSaturated) {
- constexpr size_t kNumThreads = 10;
- constexpr size_t kNumCalls = kNumThreads + 3;
- constexpr size_t kSleepMs = 500;
-
- auto proc = createRpcTestSocketServerProcess({.numThreads = kNumThreads});
-
+void BinderRpc::testThreadPoolOverSaturated(sp<IBinderRpcTest> iface, size_t numCalls,
+ size_t sleepMs) {
size_t epochMsBefore = epochMillis();
std::vector<std::thread> ts;
- for (size_t i = 0; i < kNumCalls; i++) {
- ts.push_back(std::thread([&] { proc.rootIface->sleepMs(kSleepMs); }));
+ for (size_t i = 0; i < numCalls; i++) {
+ ts.push_back(std::thread([&] { iface->sleepMs(sleepMs); }));
}
for (auto& t : ts) t.join();
size_t epochMsAfter = epochMillis();
- EXPECT_GE(epochMsAfter, epochMsBefore + 2 * kSleepMs);
+ EXPECT_GE(epochMsAfter, epochMsBefore + 2 * sleepMs);
// Potential flake, but make sure calls are handled in parallel.
- EXPECT_LE(epochMsAfter, epochMsBefore + 3 * kSleepMs);
+ EXPECT_LE(epochMsAfter, epochMsBefore + 3 * sleepMs);
+}
+
+TEST_P(BinderRpc, ThreadPoolOverSaturated) {
+ constexpr size_t kNumThreads = 10;
+ constexpr size_t kNumCalls = kNumThreads + 3;
+ auto proc = createRpcTestSocketServerProcess({.numThreads = kNumThreads});
+ testThreadPoolOverSaturated(proc.rootIface, kNumCalls);
+}
+
+TEST_P(BinderRpc, ThreadPoolLimitOutgoing) {
+ constexpr size_t kNumThreads = 20;
+ constexpr size_t kNumOutgoingConnections = 10;
+ constexpr size_t kNumCalls = kNumOutgoingConnections + 3;
+ auto proc = createRpcTestSocketServerProcess(
+ {.numThreads = kNumThreads, .numOutgoingConnections = kNumOutgoingConnections});
+ testThreadPoolOverSaturated(proc.rootIface, kNumCalls);
}
TEST_P(BinderRpc, ThreadingStressTest) {