diff --git a/libs/hwui/pipeline/skia/ShaderCache.cpp b/libs/hwui/pipeline/skia/ShaderCache.cpp
index a55de95..9ff59ef 100644
--- a/libs/hwui/pipeline/skia/ShaderCache.cpp
+++ b/libs/hwui/pipeline/skia/ShaderCache.cpp
@@ -175,14 +175,13 @@
 
 void ShaderCache::saveToDiskLocked() {
     ATRACE_NAME("ShaderCache::saveToDiskLocked");
-    if (mInitialized && mBlobCache && mSavePending) {
+    if (mInitialized && mBlobCache) {
         if (mIDHash.size()) {
             auto key = sIDKey;
             set(mBlobCache.get(), &key, sizeof(key), mIDHash.data(), mIDHash.size());
         }
         mBlobCache->writeToFile();
     }
-    mSavePending = false;
 }
 
 void ShaderCache::store(const SkData& key, const SkData& data, const SkString& /*description*/) {
@@ -225,10 +224,10 @@
     }
     set(bc, key.data(), keySize, value, valueSize);
 
-    if (!mSavePending && mDeferredSaveDelay > 0) {
+    if (!mSavePending && mDeferredSaveDelayMs > 0) {
         mSavePending = true;
         std::thread deferredSaveThread([this]() {
-            sleep(mDeferredSaveDelay);
+            usleep(mDeferredSaveDelayMs * 1000);  // milliseconds to microseconds
             std::lock_guard<std::mutex> lock(mMutex);
             // Store file on disk if there a new shader or Vulkan pipeline cache size changed.
             if (mCacheDirty || mNewPipelineCacheSize != mOldPipelineCacheSize) {
@@ -237,6 +236,7 @@
                 mTryToStorePipelineCache = false;
                 mCacheDirty = false;
             }
+            mSavePending = false;
         });
         deferredSaveThread.detach();
     }
diff --git a/libs/hwui/pipeline/skia/ShaderCache.h b/libs/hwui/pipeline/skia/ShaderCache.h
index bc35fa5f..f5506d6 100644
--- a/libs/hwui/pipeline/skia/ShaderCache.h
+++ b/libs/hwui/pipeline/skia/ShaderCache.h
@@ -156,7 +156,8 @@
      * pending.  Each time a key/value pair is inserted into the cache via
      * load, a deferred save is initiated if one is not already pending.
      * This will wait some amount of time and then trigger a save of the cache
-     * contents to disk.
+     * contents to disk, unless mDeferredSaveDelayMs is 0 in which case saving
+     * is disabled.
      */
     bool mSavePending = false;
 
@@ -166,9 +167,11 @@
     size_t mObservedBlobValueSize = 20 * 1024;
 
     /**
-     *  The time in seconds to wait before saving newly inserted cache entries.
+     *  The time in milliseconds to wait before saving newly inserted cache entries.
+     *
+     *  WARNING: setting this to 0 will disable writing the cache to disk.
      */
-    unsigned int mDeferredSaveDelay = 4;
+    unsigned int mDeferredSaveDelayMs = 4 * 1000;
 
     /**
      * "mMutex" is the mutex used to prevent concurrent access to the member
diff --git a/libs/hwui/tests/unit/ShaderCacheTests.cpp b/libs/hwui/tests/unit/ShaderCacheTests.cpp
index 576e946..7bcd45c 100644
--- a/libs/hwui/tests/unit/ShaderCacheTests.cpp
+++ b/libs/hwui/tests/unit/ShaderCacheTests.cpp
@@ -14,6 +14,10 @@
  * limitations under the License.
  */
 
+#include <GrDirectContext.h>
+#include <Properties.h>
+#include <SkData.h>
+#include <SkRefCnt.h>
 #include <cutils/properties.h>
 #include <dirent.h>
 #include <errno.h>
@@ -22,11 +26,12 @@
 #include <stdlib.h>
 #include <sys/types.h>
 #include <utils/Log.h>
+
 #include <cstdint>
+
 #include "FileBlobCache.h"
 #include "pipeline/skia/ShaderCache.h"
-#include <SkData.h>
-#include <SkRefCnt.h>
+#include "tests/common/TestUtils.h"
 
 using namespace android::uirenderer::skiapipeline;
 
@@ -37,11 +42,38 @@
 class ShaderCacheTestUtils {
 public:
     /**
-     * "setSaveDelay" sets the time in seconds to wait before saving newly inserted cache entries.
-     * If set to 0, then deferred save is disabled.
+     * Hack to reset all member variables of the given cache to their default / initial values.
+     *
+     * WARNING: this must be kept up to date manually, since ShaderCache's parent disables just
+     * reassigning a new instance.
      */
-    static void setSaveDelay(ShaderCache& cache, unsigned int saveDelay) {
-        cache.mDeferredSaveDelay = saveDelay;
+    static void reinitializeAllFields(ShaderCache& cache) {
+        ShaderCache newCache = ShaderCache();
+        std::lock_guard<std::mutex> lock(cache.mMutex);
+        // By order of declaration
+        cache.mInitialized = newCache.mInitialized;
+        cache.mBlobCache.reset(nullptr);
+        cache.mFilename = newCache.mFilename;
+        cache.mIDHash.clear();
+        cache.mSavePending = newCache.mSavePending;
+        cache.mObservedBlobValueSize = newCache.mObservedBlobValueSize;
+        cache.mDeferredSaveDelayMs = newCache.mDeferredSaveDelayMs;
+        cache.mTryToStorePipelineCache = newCache.mTryToStorePipelineCache;
+        cache.mInStoreVkPipelineInProgress = newCache.mInStoreVkPipelineInProgress;
+        cache.mNewPipelineCacheSize = newCache.mNewPipelineCacheSize;
+        cache.mOldPipelineCacheSize = newCache.mOldPipelineCacheSize;
+        cache.mCacheDirty = newCache.mCacheDirty;
+        cache.mNumShadersCachedInRam = newCache.mNumShadersCachedInRam;
+    }
+
+    /**
+     * "setSaveDelayMs" sets the time in milliseconds to wait before saving newly inserted cache
+     * entries. If set to 0, then deferred save is disabled, and "saveToDiskLocked" must be called
+     * manually, as seen in the "terminate" testing helper function.
+     */
+    static void setSaveDelayMs(ShaderCache& cache, unsigned int saveDelayMs) {
+        std::lock_guard<std::mutex> lock(cache.mMutex);
+        cache.mDeferredSaveDelayMs = saveDelayMs;
     }
 
     /**
@@ -50,8 +82,9 @@
      */
     static void terminate(ShaderCache& cache, bool saveContent) {
         std::lock_guard<std::mutex> lock(cache.mMutex);
-        cache.mSavePending = saveContent;
-        cache.saveToDiskLocked();
+        if (saveContent) {
+            cache.saveToDiskLocked();
+        }
         cache.mBlobCache = NULL;
     }
 
@@ -62,6 +95,38 @@
     static bool validateCache(ShaderCache& cache, std::vector<T> hash) {
         return cache.validateCache(hash.data(), hash.size() * sizeof(T));
     }
+
+    /**
+     * Waits until cache::mSavePending is false, checking every 0.1 ms *while the mutex is free*.
+     *
+     * Fails if there was no save pending, or if the cache was already being written to disk, or if
+     * timeoutMs is exceeded.
+     *
+     * Note: timeoutMs only guards against mSavePending getting stuck like in b/268205519, and
+     * cannot protect against mutex-based deadlock. Reaching timeoutMs implies something is broken,
+     * so setting it to a sufficiently large value will not delay execution in the happy state.
+     */
+    static void waitForPendingSave(ShaderCache& cache, const int timeoutMs = 50) {
+        {
+            std::lock_guard<std::mutex> lock(cache.mMutex);
+            ASSERT_TRUE(cache.mSavePending);
+        }
+        bool saving = true;
+        float elapsedMilliseconds = 0;
+        while (saving) {
+            if (elapsedMilliseconds >= timeoutMs) {
+                FAIL() << "Timed out after waiting " << timeoutMs << " ms for a pending save";
+            }
+            // This small (0.1 ms) delay is to avoid working too much while waiting for
+            // deferredSaveThread to take the mutex and start the disk write.
+            const int delayMicroseconds = 100;
+            usleep(delayMicroseconds);
+            elapsedMilliseconds += (float)delayMicroseconds / 1000;
+
+            std::lock_guard<std::mutex> lock(cache.mMutex);
+            saving = cache.mSavePending;
+        }
+    }
 };
 
 } /* namespace skiapipeline */
@@ -83,6 +148,18 @@
     return false;
 }
 
+/**
+ * Attempts to delete the given file, and asserts that either:
+ * 1. Deletion was successful, OR
+ * 2. The file did not exist.
+ *
+ * Tip: wrap calls to this in ASSERT_NO_FATAL_FAILURE(x) if a test should exit early if this fails.
+ */
+void deleteFileAssertSuccess(const std::string& filePath) {
+    int deleteResult = remove(filePath.c_str());
+    ASSERT_TRUE(0 == deleteResult || ENOENT == errno);
+}
+
 inline bool checkShader(const sk_sp<SkData>& shader1, const sk_sp<SkData>& shader2) {
     return nullptr != shader1 && nullptr != shader2 && shader1->size() == shader2->size() &&
            0 == memcmp(shader1->data(), shader2->data(), shader1->size());
@@ -93,6 +170,10 @@
     return checkShader(shader, shader2);
 }
 
+inline bool checkShader(const sk_sp<SkData>& shader, const std::string& program) {
+    return checkShader(shader, program.c_str());
+}
+
 template <typename T>
 bool checkShader(const sk_sp<SkData>& shader, std::vector<T>& program) {
     sk_sp<SkData> shader2 = SkData::MakeWithCopy(program.data(), program.size() * sizeof(T));
@@ -103,6 +184,10 @@
     shader = SkData::MakeWithCString(program);
 }
 
+void setShader(sk_sp<SkData>& shader, const std::string& program) {
+    setShader(shader, program.c_str());
+}
+
 template <typename T>
 void setShader(sk_sp<SkData>& shader, std::vector<T>& buffer) {
     shader = SkData::MakeWithCopy(buffer.data(), buffer.size() * sizeof(T));
@@ -126,13 +211,13 @@
     std::string cacheFile2 = getExternalStorageFolder() + "/shaderCacheTest2";
 
     // remove any test files from previous test run
-    int deleteFile = remove(cacheFile1.c_str());
-    ASSERT_TRUE(0 == deleteFile || ENOENT == errno);
+    ASSERT_NO_FATAL_FAILURE(deleteFileAssertSuccess(cacheFile1));
+    ASSERT_NO_FATAL_FAILURE(deleteFileAssertSuccess(cacheFile2));
     std::srand(0);
 
     // read the cache from a file that does not exist
     ShaderCache::get().setFilename(cacheFile1.c_str());
-    ShaderCacheTestUtils::setSaveDelay(ShaderCache::get(), 0);  // disable deferred save
+    ShaderCacheTestUtils::setSaveDelayMs(ShaderCache::get(), 0);  // disable deferred save
     ShaderCache::get().initShaderDiskCache();
 
     // read a key - should not be found since the cache is empty
@@ -186,7 +271,8 @@
     ASSERT_TRUE(checkShader(outVS2, dataBuffer));
 
     ShaderCacheTestUtils::terminate(ShaderCache::get(), false);
-    remove(cacheFile1.c_str());
+    ASSERT_NO_FATAL_FAILURE(deleteFileAssertSuccess(cacheFile1));
+    ASSERT_NO_FATAL_FAILURE(deleteFileAssertSuccess(cacheFile2));
 }
 
 TEST(ShaderCacheTest, testCacheValidation) {
@@ -198,13 +284,13 @@
     std::string cacheFile2 = getExternalStorageFolder() + "/shaderCacheTest2";
 
     // remove any test files from previous test run
-    int deleteFile = remove(cacheFile1.c_str());
-    ASSERT_TRUE(0 == deleteFile || ENOENT == errno);
+    ASSERT_NO_FATAL_FAILURE(deleteFileAssertSuccess(cacheFile1));
+    ASSERT_NO_FATAL_FAILURE(deleteFileAssertSuccess(cacheFile2));
     std::srand(0);
 
     // generate identity and read the cache from a file that does not exist
     ShaderCache::get().setFilename(cacheFile1.c_str());
-    ShaderCacheTestUtils::setSaveDelay(ShaderCache::get(), 0);  // disable deferred save
+    ShaderCacheTestUtils::setSaveDelayMs(ShaderCache::get(), 0);  // disable deferred save
     std::vector<uint8_t> identity(1024);
     genRandomData(identity);
     ShaderCache::get().initShaderDiskCache(
@@ -278,7 +364,81 @@
     }
 
     ShaderCacheTestUtils::terminate(ShaderCache::get(), false);
-    remove(cacheFile1.c_str());
+    ASSERT_NO_FATAL_FAILURE(deleteFileAssertSuccess(cacheFile1));
+    ASSERT_NO_FATAL_FAILURE(deleteFileAssertSuccess(cacheFile2));
+}
+
+using namespace android::uirenderer;
+RENDERTHREAD_SKIA_PIPELINE_TEST(ShaderCacheTest, testOnVkFrameFlushed) {
+    if (Properties::getRenderPipelineType() != RenderPipelineType::SkiaVulkan) {
+        // RENDERTHREAD_SKIA_PIPELINE_TEST declares both SkiaVK and SkiaGL variants.
+        GTEST_SKIP() << "This test is only applicable to RenderPipelineType::SkiaVulkan";
+    }
+    if (!folderExist(getExternalStorageFolder())) {
+        // Don't run the test if external storage folder is not available
+        return;
+    }
+    std::string cacheFile = getExternalStorageFolder() + "/shaderCacheTest";
+    GrDirectContext* grContext = renderThread.getGrContext();
+
+    // Remove any test files from previous test run
+    ASSERT_NO_FATAL_FAILURE(deleteFileAssertSuccess(cacheFile));
+
+    // The first iteration of this loop is to save an initial VkPipelineCache data blob to disk,
+    // which sets up the second iteration for a common scenario of comparing a "new" VkPipelineCache
+    // blob passed to "store" against the same blob that's already in the persistent cache from a
+    // previous launch. "reinitializeAllFields" is critical to emulate each iteration being as close
+    // to the state of a freshly launched app as possible, as the initial values of member variables
+    // like mInStoreVkPipelineInProgress and mOldPipelineCacheSize are critical to catch issues
+    // such as b/268205519
+    for (int flushIteration = 1; flushIteration <= 2; flushIteration++) {
+        SCOPED_TRACE("Frame flush iteration " + std::to_string(flushIteration));
+        // Reset *all* in-memory data and reload the cache from disk.
+        ShaderCacheTestUtils::reinitializeAllFields(ShaderCache::get());
+        ShaderCacheTestUtils::setSaveDelayMs(ShaderCache::get(), 10);  // Delay must be > 0 to save.
+        ShaderCache::get().setFilename(cacheFile.c_str());
+        ShaderCache::get().initShaderDiskCache();
+
+        // 1st iteration: store pipeline data to be read back on a subsequent "boot" of the "app".
+        // 2nd iteration: ensure that an initial frame flush (without storing any shaders) given the
+        // same pipeline data that's already on disk doesn't break the cache.
+        ShaderCache::get().onVkFrameFlushed(grContext);
+        ASSERT_NO_FATAL_FAILURE(ShaderCacheTestUtils::waitForPendingSave(ShaderCache::get()));
+    }
+
+    constexpr char shader1[] = "sassas";
+    constexpr char shader2[] = "someVS";
+    constexpr int numIterations = 3;
+    // Also do n iterations of separate "store some shaders then flush the frame" pairs to just
+    // double-check the cache also doesn't get stuck from that use case.
+    for (int saveIteration = 1; saveIteration <= numIterations; saveIteration++) {
+        SCOPED_TRACE("Shader save iteration " + std::to_string(saveIteration));
+        // Write twice to the in-memory cache, which should start a deferred save with both queued.
+        sk_sp<SkData> inVS;
+        setShader(inVS, shader1 + std::to_string(saveIteration));
+        ShaderCache::get().store(GrProgramDescTest(100), *inVS.get(), SkString());
+        setShader(inVS, shader2 + std::to_string(saveIteration));
+        ShaderCache::get().store(GrProgramDescTest(432), *inVS.get(), SkString());
+
+        // Simulate flush to also save latest pipeline info.
+        ShaderCache::get().onVkFrameFlushed(grContext);
+        ASSERT_NO_FATAL_FAILURE(ShaderCacheTestUtils::waitForPendingSave(ShaderCache::get()));
+    }
+
+    // Reload from disk to ensure saving succeeded.
+    ShaderCacheTestUtils::terminate(ShaderCache::get(), false);
+    ShaderCache::get().initShaderDiskCache();
+
+    // Read twice, ensure equal to last store.
+    sk_sp<SkData> outVS;
+    ASSERT_NE((outVS = ShaderCache::get().load(GrProgramDescTest(100))), sk_sp<SkData>());
+    ASSERT_TRUE(checkShader(outVS, shader1 + std::to_string(numIterations)));
+    ASSERT_NE((outVS = ShaderCache::get().load(GrProgramDescTest(432))), sk_sp<SkData>());
+    ASSERT_TRUE(checkShader(outVS, shader2 + std::to_string(numIterations)));
+
+    // Clean up.
+    ShaderCacheTestUtils::terminate(ShaderCache::get(), false);
+    ASSERT_NO_FATAL_FAILURE(deleteFileAssertSuccess(cacheFile));
 }
 
 }  // namespace