beta7: perf tuning — leveldb max_open_files scaling + HTTP workqueue defaults

src/dbwrapper.cpp

@@ -21,7 +21,17 @@ static leveldb::Options GetOptions(size_t nCacheSize)
     options.write_buffer_size = nCacheSize / 4; // up to two write buffers may be held in memory simultaneously
     options.filter_policy = leveldb::NewBloomFilterPolicy(10);
     options.compression = leveldb::kNoCompression;
-    options.max_open_files = 64;
+    // Scale the open-file cache with the configured DB cache so a large block
+    // index doesn't thrash file descriptors (matches Bitcoin Core's later
+    // scaling): 64 for small caches, up to 1000 for large ones. Each ~2MiB
+    // table is held open via these, so this is purely an I/O/FD tuning and
+    // does not change any stored or computed value.
+    options.max_open_files = 1000;
+    if (nCacheSize < 100 * 1048576) {
+        // Use the conservative default for small caches (e.g. unit tests,
+        // low-memory configs) to keep FD usage modest.
+        options.max_open_files = 64;
+    }
     if (leveldb::kMajorVersion > 1 || (leveldb::kMajorVersion == 1 && leveldb::kMinorVersion >= 16)) {
         // LevelDB versions before 1.16 consider short writes to be corruption. Only trigger error
         // on corruption in later versions.

src/httpserver.h

@@ -11,8 +11,11 @@
 #include <boost/scoped_ptr.hpp>
 #include <boost/function.hpp>
 
-static const int DEFAULT_HTTP_THREADS=4;
-static const int DEFAULT_HTTP_WORKQUEUE=16;
+// Raised from 4/16 to avoid "Work queue depth exceeded" HTTP 500s under load
+// (e.g. wallet/GUI bursts of concurrent RPC calls). Still user-overridable via
+// -rpcthreads / -rpcworkqueue; config-only, no consensus or value impact.
+static const int DEFAULT_HTTP_THREADS=8;
+static const int DEFAULT_HTTP_WORKQUEUE=256;
 static const int DEFAULT_HTTP_SERVER_TIMEOUT=30;
 
 struct evhttp_request;