1 files changed, 28 insertions, 9 deletions

diff --git a/src/util.cpp b/src/util.cpp
index 08ee6b8b8..6f812d910 100644
--- a/src/util.cpp
+++ b/src/util.cpp
@@ -72,6 +72,10 @@
 #include <sys/prctl.h>
 #endif
 
+#ifdef HAVE_MALLOPT_ARENA_MAX
+#include <malloc.h>
+#endif
+
 #include <boost/algorithm/string/case_conv.hpp> // for to_lower()
 #include <boost/algorithm/string/join.hpp>
 #include <boost/algorithm/string/predicate.hpp> // for startswith() and endswith()
@@ -214,12 +218,13 @@ void OpenDebugLog()
     assert(vMsgsBeforeOpenLog);
     boost::filesystem::path pathDebug = GetDataDir() / "debug.log";
     fileout = fopen(pathDebug.string().c_str(), "a");
-    if (fileout) setbuf(fileout, NULL); // unbuffered
-
-    // dump buffered messages from before we opened the log
-    while (!vMsgsBeforeOpenLog->empty()) {
-        FileWriteStr(vMsgsBeforeOpenLog->front(), fileout);
-        vMsgsBeforeOpenLog->pop_front();
+    if (fileout) {
+        setbuf(fileout, NULL); // unbuffered
+        // dump buffered messages from before we opened the log
+        while (!vMsgsBeforeOpenLog->empty()) {
+            FileWriteStr(vMsgsBeforeOpenLog->front(), fileout);
+            vMsgsBeforeOpenLog->pop_front();
+        }
     }
 
     delete vMsgsBeforeOpenLog;
@@ -723,13 +728,17 @@ void AllocateFileRange(FILE *file, unsigned int offset, unsigned int length) {
 
 void ShrinkDebugFile()
 {
+    // Amount of debug.log to save at end when shrinking (must fit in memory)
+    constexpr size_t RECENT_DEBUG_HISTORY_SIZE = 10 * 1000000;
     // Scroll debug.log if it's getting too big
     boost::filesystem::path pathLog = GetDataDir() / "debug.log";
     FILE* file = fopen(pathLog.string().c_str(), "r");
-    if (file && boost::filesystem::file_size(pathLog) > 10 * 1000000)
+    // If debug.log file is more than 10% bigger the RECENT_DEBUG_HISTORY_SIZE
+    // trim it down by saving only the last RECENT_DEBUG_HISTORY_SIZE bytes
+    if (file && boost::filesystem::file_size(pathLog) > 11 * (RECENT_DEBUG_HISTORY_SIZE / 10))
     {
         // Restart the file with some of the end
-        std::vector <char> vch(200000,0);
+        std::vector<char> vch(RECENT_DEBUG_HISTORY_SIZE, 0);
         fseek(file, -((long)vch.size()), SEEK_END);
         int nBytes = fread(vch.data(), 1, vch.size(), file);
         fclose(file);
@@ -787,6 +796,16 @@ void RenameThread(const char* name)
 
 void SetupEnvironment()
 {
+#ifdef HAVE_MALLOPT_ARENA_MAX
+    // glibc-specific: On 32-bit systems set the number of arenas to 1.
+    // By default, since glibc 2.10, the C library will create up to two heap
+    // arenas per core. This is known to cause excessive virtual address space
+    // usage in our usage. Work around it by setting the maximum number of
+    // arenas to 1.
+    if (sizeof(void*) == 4) {
+        mallopt(M_ARENA_MAX, 1);
+    }
+#endif
     // On most POSIX systems (e.g. Linux, but not BSD) the environment's locale
     // may be invalid, in which case the "C" locale is used as fallback.
 #if !defined(WIN32) && !defined(MAC_OSX) && !defined(__FreeBSD__) && !defined(__OpenBSD__)
@@ -834,4 +853,4 @@ std::string CopyrightHolders(const std::string& strPrefix)
         strCopyrightHolders += "\n" + strPrefix + "The Bitcoin Core developers";
     }
     return strCopyrightHolders;
-}
+}
\ No newline at end of file