1.1 --- a/src/share/vm/utilities/ostream.cpp Mon Nov 18 23:41:06 2019 -0500
1.2 +++ b/src/share/vm/utilities/ostream.cpp Thu Apr 09 13:07:11 2020 +0000
1.3 @@ -27,6 +27,7 @@
1.4 #include "gc_implementation/shared/gcId.hpp"
1.5 #include "oops/oop.inline.hpp"
1.6 #include "runtime/arguments.hpp"
1.7 +#include "runtime/mutexLocker.hpp"
1.8 #include "runtime/os.hpp"
1.9 #include "utilities/defaultStream.hpp"
1.10 #include "utilities/ostream.hpp"
1.11 @@ -794,9 +795,11 @@
1.12 FREE_C_HEAP_ARRAY(char, _file_name, mtInternal);
1.13 _file_name = NULL;
1.14 }
1.15 +
1.16 + delete _file_lock;
1.17 }
1.18
1.19 -gcLogFileStream::gcLogFileStream(const char* file_name) {
1.20 +gcLogFileStream::gcLogFileStream(const char* file_name) : _file_lock(NULL) {
1.21 _cur_file_num = 0;
1.22 _bytes_written = 0L;
1.23 _file_name = make_log_name(file_name, NULL);
1.24 @@ -819,6 +822,10 @@
1.25 if (_file != NULL) {
1.26 _need_close = true;
1.27 dump_loggc_header();
1.28 +
1.29 + if (UseGCLogFileRotation) {
1.30 + _file_lock = new Mutex(Mutex::leaf, "GCLogFile");
1.31 + }
1.32 } else {
1.33 warning("Cannot open file %s due to %s\n", _file_name, strerror(errno));
1.34 _need_close = false;
1.35 @@ -827,21 +834,54 @@
1.36
1.37 void gcLogFileStream::write(const char* s, size_t len) {
1.38 if (_file != NULL) {
1.39 - size_t count = fwrite(s, 1, len, _file);
1.40 - _bytes_written += count;
1.41 + // we can't use Thread::current() here because thread may be NULL
1.42 + // in early stage(ostream_init_log)
1.43 + Thread* thread = ThreadLocalStorage::thread();
1.44 +
1.45 + // avoid the mutex in the following cases
1.46 + // 1) ThreadLocalStorage::thread() hasn't been initialized
1.47 + // 2) _file_lock is not in use.
1.48 + // 3) current() is VMThread and its reentry flag is set
1.49 + if (!thread || !_file_lock || (thread->is_VM_thread()
1.50 + && ((VMThread* )thread)->is_gclog_reentry())) {
1.51 + size_t count = fwrite(s, 1, len, _file);
1.52 + _bytes_written += count;
1.53 + }
1.54 + else {
1.55 + MutexLockerEx ml(_file_lock, Mutex::_no_safepoint_check_flag);
1.56 + size_t count = fwrite(s, 1, len, _file);
1.57 + _bytes_written += count;
1.58 + }
1.59 }
1.60 update_position(s, len);
1.61 }
1.62
1.63 -// rotate_log must be called from VMThread at safepoint. In case need change parameters
1.64 +// rotate_log must be called from VMThread at a safepoint. In case need change parameters
1.65 // for gc log rotation from thread other than VMThread, a sub type of VM_Operation
1.66 // should be created and be submitted to VMThread's operation queue. DO NOT call this
1.67 -// function directly. Currently, it is safe to rotate log at safepoint through VMThread.
1.68 -// That is, no mutator threads and concurrent GC threads run parallel with VMThread to
1.69 -// write to gc log file at safepoint. If in future, changes made for mutator threads or
1.70 -// concurrent GC threads to run parallel with VMThread at safepoint, write and rotate_log
1.71 -// must be synchronized.
1.72 +// function directly. It is safe to rotate log through VMThread because
1.73 +// no mutator threads run concurrently with the VMThread, and GC threads that run
1.74 +// concurrently with the VMThread are synchronized in write and rotate_log via _file_lock.
1.75 +// rotate_log can write log entries, so write supports reentry for it.
1.76 void gcLogFileStream::rotate_log(bool force, outputStream* out) {
1.77 + #ifdef ASSERT
1.78 + Thread *thread = Thread::current();
1.79 + assert(thread == NULL ||
1.80 + (thread->is_VM_thread() && SafepointSynchronize::is_at_safepoint()),
1.81 + "Must be VMThread at safepoint");
1.82 + #endif
1.83 +
1.84 + VMThread* vmthread = VMThread::vm_thread();
1.85 + {
1.86 + // nop if _file_lock is NULL.
1.87 + MutexLockerEx ml(_file_lock, Mutex::_no_safepoint_check_flag);
1.88 + vmthread->set_gclog_reentry(true);
1.89 + rotate_log_impl(force, out);
1.90 + vmthread->set_gclog_reentry(false);
1.91 + }
1.92 +}
1.93 +
1.94 +void gcLogFileStream::rotate_log_impl(bool force, outputStream* out) {
1.95 char time_msg[O_BUFLEN];
1.96 char time_str[EXTRACHARLEN];
1.97 char current_file_name[JVM_MAXPATHLEN];
1.98 @@ -851,12 +891,6 @@
1.99 return;
1.100 }
1.101
1.102 -#ifdef ASSERT
1.103 - Thread *thread = Thread::current();
1.104 - assert(thread == NULL ||
1.105 - (thread->is_VM_thread() && SafepointSynchronize::is_at_safepoint()),
1.106 - "Must be VMThread at safepoint");
1.107 -#endif
1.108 if (NumberOfGCLogFiles == 1) {
1.109 // rotate in same file
1.110 rewind();
