When use pulsar::Message msg = pulsar::MessageBuilder().setContent(sMsg).build() to Create Message, sometimes it will occur segment fault

(gdb) bt
#0 pop (this=0x7f2b58df7900) at pulsar-client-3.4/lib/ObjectPool.h:74
#1 allocate (this=0x7f2b58df7900) at pulsar-client-3.4/lib/ObjectPool.h:134
#2 allocate (n=1, this=) at pulsar-client-3.4/lib/ObjectPool.h:167
#3 allocate (__a=, __n=1) at /usr/local/gcc-4.9.3/include/c++/4.9.3/bits/alloc_traits.h:357
#4 __shared_count > (__a=..., this=0x7f2b3e589ea8)
at /usr/local/gcc-4.9.3/include/c++/4.9.3/bits/shared_ptr_base.h:616
#5 __shared_ptr > (__a=..., __tag=..., this=0x7f2b3e589ea0,
this@entry=)
at /usr/local/gcc-4.9.3/include/c++/4.9.3/bits/shared_ptr_base.h:1090
#6 shared_ptr > (__a=..., __tag=..., this=0x7f2b3e589ea0)
at /usr/local/gcc-4.9.3/include/c++/4.9.3/bits/shared_ptr.h:316
#7 allocate_shared > (__a=...)
at /usr/local/gcc-4.9.3/include/c++/4.9.3/bits/shared_ptr.h:588
#8 create (this=0x2622ba0 ) at pulsar-client-3.4/lib/ObjectPool.h:212
#9 pulsar::MessageBuilder::createMessageImpl () at pulsar-client-3.4/lib/MessageBuilder.cc:42

(gdb) print head_
Cannot access memory at address 0x7f2b58df7900
(gdb) print result
$1 = (void *) 0x1

void* pop() {
if (!head_) {
// size = 0
std::lock_guard lock(mutex_);

if (!globalPool_) {
return NULL;
}

GlobalPool* poolEntry = globalPool_;
head_ = globalPool_->node_;
pushSize_ += globalPool_->nodeCount_;
globalNodeCount_ -= globalPool_->nodeCount_;
globalPool_ = globalPool_->next_;
delete poolEntry;
}
void* result = head_;
if (result) {
head_ = head_->next;
pushSize_--;
}
return result;
}

首先复现 pulsar-client-3.4/lib/MessageBuilder.cc:42 中 MessageBuilder::createMessageImpl 的 segfault，并将 GDB trace 作为初始症状。检查 ObjectPool.h，尤其是 pop、allocate 和 create，并确定 head_ 或 pool 状态为何会失效。完成的标准是：在报告的条件下使用 MessageBuilder 构造消息不再崩溃，并为该故障添加回归检查。

由索引模型根据 Issue 内容生成。